2. A rifle can shoot a 4.00 g bullet at a speed of 998 m/s.
a. Find the kinetic energy of the bullet.
b. What work is done on the bullet if it starts from rest?
c. If the work is done over a distance of 0.75 m, what is the average
force on the bullet?
d. If the bullet comes to rest after penetrating 1.50 cm into a piece of
metal, what is the magnitude of the force bringing it to rest?
Posted Thu Oct 27, 2022 at 9:11 am

Answers

Answer 1

a) The kinetic energy of the bullet is 1.996 joule.

b) The total work done on it is 1.996 joule.

c)  The average force on the bullet is 2.661 N.

d) The  magnitude of the force bringing it to rest is 1.33 N.

What is speed?

Speed is distance travelled by the object per unit time. Due to having no direction and only having magnitude, speed is a scalar quantity With SI unit meter/second.

Given that: . A rifle can shoot a 4.00 g bullet at a speed of 998 m/s.

a) the kinetic energy of the bullet = (4.00/1000)×998/2 joule = 1.996 joule.

b)  If it starts from rest, the total work done on it = kinetic energy of it = 1.996 joule.

c) If the work is done over a distance of 0.75 m, the average force on the bullet is = work done/distance =  1.996/0.75  N = 2.661 N.

d)  If the bullet comes to rest after penetrating 1.50 cm into a piece of

metal, the magnitude of the force bringing it to rest is = 1.996/1.50 N = 1.33 N.

Learn more about speed here:

https://brainly.com/question/28224010

#SPJ1


Related Questions

What happens when magnesium becomes a 2+ ion?

Answers

When magnesium becomes a 2+ ion its becomes cation that is positive charge.

Due to its 12 protons and membership in group 2 of the periodic table, magnesium possesses two electrons in its outer shell (positive charges)

We know that ionic substances consist of two ions, one of which is a positive cation and the other is a negative anion. For instance, cations and anion are produced when we divide ionic substances into their individual ions.

(a), Breaking of [tex]$\mathrm{MgBr}_2$[/tex] into ions '

[tex]\left.\mathrm{MgBr}_2_(aq) \longrightarrow \mathrm{Mg}_{(\mathrm{aq})}^{2+}+2 \mathrm{Br}_{\left(a q_1\right)}{ }^2\right[/tex]

Cation formula [tex]$=Mg^{2+} (a q)$[/tex]

Anion Formula [tex]$=\mathrm{Br}^{\ominus}(a q)$[/tex]

For more such question on magnesium.

https://brainly.com/question/27798376

#SPJ4

what is the mathematical formula to calculate resistance when the value of voltage and current are known

Answers

Voltage divided by current equals resistance (R=VI R = V I). Ohm's Law (E = IR) is as basic to electronics students as Einstein's Relativity equation (E = mc2) is to physicists.

When written down, voltage = current x resistance, or volts = amps x ohms, or V = A x. According to Ohm's law, the current flowing through a conductor between two places is proportional to the voltage across the two points. According to Ohm's law, the current flowing through a conductor between two places is proportional to the voltage across the two points. The formula for Ohm's law is V I. As a result, V = RI, where R is a constant known as resistance.

Learn more about voltage here-

https://brainly.com/question/13396105

#SPJ4

a ball is kicked at an angle of 40 degrees with the ground with the initial velocity of 15m/s. the ball reaches point b after 1.5 seconds. 1. what is the initial velocity in the y-direction? 2. what is the final velocity in the x-direction (at point b)? 3. what is the range, xb, in meters? 4. what is the height, hb, when the ball reaches point b, in meters?

Answers

(1) The initial velocity in the y-direction is 9.64 m/s.

(2) The final velocity in the x-direction is 11.5 m/s.

(3)  The range, xb, of the ball is 22.6 m.

(4) The maximum height reached by the ball is 4.74 m.

What is the initial vertical component of the velocity?

The initial vertical component of the velocity is calculated using the following kinematic equation.

Vy = V sinθ

where;

V is the initial velocity θ is the angle of projection of the ball

Vy = V sinθ

Vy = ( 15 m/s ) x ( sin 40 )

Vy = 9.64 m/s

The final velocity in the x-direction is calculated as follows;

Vₓf = Vxi = V cosθ

where;

Vₓf is the final horizontal velocity Vₓi is the initial horizontal velocity

Vₓf  = ( 15 m/s ) x ( cos 40 )

Vₓf  = 11.5 m/s

The range of the ball is calculated as follows;

R = v² sin (2θ) / g

R = ( 15² sin (2 x 40) ) / 9.8

R = 22.6 m

The maximum height reached by the ball is calculated as;

H = v² sin²θ / 2g

H = ( 15² x ( sin 40 )² ) / (2 x 9.8)

H = 4.74 m

Learn more about maximum height of projectile here: https://brainly.com/question/12870645

#SPJ1

Why is CO2 considered a major factor in climate change?

Answers

Carbon dioxide is the planet's most important greenhouse gas because it both absorbs and radiates heat.

Is CO2 the primary factor causing climate change?

The main cause of global warming is CO2, which is created by human activity.Its atmospheric concentration increased by 48% by 2020 compared to pre-industrial levels (before 1750).Human activities can produce smaller amounts of other greenhouse gases.

What really is CO2 and why does it relate to global warming?

A greenhouse gas is carbon dioxide (CO2).As a result, the interior becomes warmer and the effect is similar to that of a greenhouse's glass.This impact is crucial since without the Carbon dioxide that really is present in the atmosphere naturally, Earth may be too chilly for life to exist on it.

To know more about climate change visit:

https://brainly.com/question/28779953

#SPJ4

What is kinetic energy short answer?

Answers

Energy possessed due to its motion

What is the speed of EM waves in a vacuum in km s?

Answers

All electromagnetic waves travel at the same speed in a vacuum, which is 300,000 km/sec (186,000 mph). This results from the electromagnetic waves' oscillating nature.

How fast is an electromagnetic wave in a vacuum?

In general, we say that light moves in waves and that all electromagnetic radiation moves through a vacuum at a speed of around 3.0 * 108 meters per second. Nothing can move faster than the speed of light, which is what we refer to as.

What is the vacuum's speed?

The universal scientific constant known as c—the speed of light in a vacuum—is significant in many branches of physics. The exact value of the speed of light, c, is 299,792,458 meters per second.

To know more about electromagnetic waves visit:-'

https://brainly.com/question/3101711

#SPJ4

why are the cross-sections of metal beams in the shape of the letter i instead of solid rectangles?

Answers

The cross-sections of metal beams in the shape of the letter I instead of solid rectangles because I beam is used horizontally, the stress is more at the top and in the bottom, and the middle is a stress free region.

Any cross section of the beam experiences bending and shearing stresses as a result of forces and couplings operating on it.

In an I beam, high weights can be carried while weighing less than in a rectangular beam.

The cross sections of metal beams are in the shape of letter I instead of solid rectangles to reduce the weight of the beam while preserving the resistance to bending.

To know more about beams:

https://brainly.com/question/28232038

#SPJ4

The greater efficiency achieved with the curved blades of a pelton wheel is due to

Answers

The greater efficiency achieved with the curved blades of a Pelton wheel is due to the fact that the curved shape of the blades allows them to more effectively capture and use the energy of the water jet.

In a Pelton wheel, water is jetted through a nozzle onto the blades of a turbine, which rotates and converts the energy of the water jet into mechanical work. The shape of the blades plays a significant role in the efficiency of the turbine. Curved blades are more efficient than straight blades because they can capture and use more of the kinetic energy of the water jet.

The curved shape of the blades creates a more efficient flow of water over the surface of the blade, which allows the blade to extract more energy from the water jet. This results in a higher torque and power output from the turbine, leading to a more efficient conversion of water energy into mechanical work.

Learn more about Pelton Wheel here:

https://brainly.com/question/20038787

#SPJ4

What is the force of friction on a sliding object?

Answers

Sliding friction is the resistance that any two items produce as they slide against one another. Kinetic friction is another name for this friction.

What forces are at work on the moving object?

The external force is the frictional motion. When the external factor is larger than the pressure of kinetic friction, acceleration happens. When the amount of kinetic friction exceeds the force of the external force, slowing (or stopping) takes place.

What kind of sliding friction is that?

When an object slides across a surface, sliding friction is regarded as a resistance to that object's motion. Think of a box that is on the ground. This surface is in close proximity to the floor's surface.

To know more about motion visit :

https://brainly.com/question/22810476

#SPJ4

Which of the following can result in deviations from Beer's law when the path length is constant? Explain your answer.
1. All radiation not absorbed by the sample is transmitted to the detector.
2. Stray light reaching the detecter.
3. Solute conc. exceeding 0.01 M.
4. The use of polychromatic radiation.
5. The sample is heterogenous Just need the ones that are correct.

Answers

There are several conditions that can result in deviations from Beer's Law when the pathlength is constant. This can cause the Beer's Law plot to become non-linear.

When the solute concentrations exceed 0.01 m. This can cause the Beer's Law plot to become flat or even inverted. The use of polychromatic radiation can also cause deviations from Beer's Law. This is because different wavelengths of light will be absorbed to different degrees by the sample.

When the pathlength is constant, the conditions that can result in deviations from Beer's law are:

1) All radiation not absorbed by the sample is transmitted to the detector.

2) The absorbing species undergoes dissociation or association.

3) The sample is homogeneous.

4) Solute concentrations exceeding 0.01 M.

5) The use of polychromatic radiation.

To know more about Wavelengths:

https://brainly.com/question/29451279

#SPJ4

At which scale factor will the pre-image and image be congruent?

Answers

The picture and the pre-image are consistent ONLY when the scale factor is 1.

What is the dilation image pre-scale image's factor?

A sort of transformation known as a dilatation enlarges or shrinks a figure (referred to as the preimage) to produce a new figure (called the image). How much larger or smaller the dilation image will be in comparison to the preimage depends on the scale factor, r.

What is the minimum scale factor required for the image to be congruent?

The scale factor and the center of dilation are used to determine the dilation transformation. The image stretches if the scaling factor is greater than 1.

To know more about pre-image visit:-

https://brainly.com/question/1809747

#SPJ4

What does FG gm1m2 r2 mean?

Answers

The expression for gravitational force was represented by the equation F, G, m1, m2, and r2.

The product of such gravitational constant as well as the masses of something like the two objects, multiplied with the square root of their distance, would be the expression for the gravitational force separating two objects.

The formula is given as:

force = (product of g, m (mass) ) / square of the d between both the objects.(r)

F = (G(gravitational force) × M × m) / r²

where,

Force = F

Gravitational Constant = G

Mass of one object = M

Mass of another object = m

Distance = r

Gravitational force seems to be the force used by the planet to pull an item toward it. Issacs Newton made the discovery after seeing an apple drop from of a tree.

To know more about Gravitational Force:

brainly.com/question/1633884

#SPJ4

For a fixed height h2 if you plot v2kin versus d, what kind of curve would you get?
1.a parabola
2.a horizontal line parallel to the x-axis
3.a straight line with a negative slope of sqrt (g/2h2)
4.there is not sufficient information to answer this question
5.a straight line with a positive slope of sqrt (g/2h2)

Answers

The plot of v²kin versus d, where, v is the velocity of motion and d is the distance travelled, is a graph of a quadratic equation, which is a parabola. The correct option is 1 a.

1 a, Parabola

What is a quadratic equation?

A quadratic equation is an equation of the form a·x² + b·x + c = 0, which is an algebraic equation with a second degree of x.

The motion of a body in free fall can be described using the following equation;

v² = u² - 2·g·h

d = u·t - 0.5·g·t²

Therefore; v² = 0² - 2·g·d = 2·g·d

v² = 2·g·d

d = v²/(2·g)

Where; g = The acceleration due to gravity ≈ 9.8 m/s²

Therefore; d ≈ v²/(2 × 9.8)

The above equation is a quadratic equation, and the graph of the equation, which is a graph of a quadratic equation is parabolic.

Please find attached the graph of v²/(2×9.81) to d, creates with MS Excel

From the shape of the graph and the function of the graph, the graph is a parabola

The correct option is 1. a parabola

Learn more about quadratic equation here:

https://brainly.com/question/776122

#SPJ1

A loaded truck can accelerate at 4.3m / (s ^ 2) It loses its load so that it is only 0.2 as massive. By what factor must the acceleration change for the same driving force?

Answers

The new acceleration of the truck  for the same driving force is 21.5  m/s^2.

What is force?

The definition of force in physics is: The push or pull on a massed object changes its velocity.

An external force is an agent that has the power to alter the resting or moving condition of a body. It has a direction and a magnitude. A spring balance can be used to calculate the Force. Newton is the SI unit of force.

Given that: A loaded truck can accelerate at 4.3m/s^2.

It loses its load so that it is only 0.2 as massive.

As force = mass × acceleration, the new acceleration of the truck for same driving force is =  (4.3 ÷ 0. 2) m/s^2

= 21.5  m/s^2

Hence, the new acceleration of the truck is 21.5  m/s^2.

Learn more about force here:

https://brainly.com/question/13191643

#SPJ1

3. gravity can best be described as: a. the tendency of masses to move towards each other b. the energy possessed by its body by virtue of its motion c. the tendency of any state of affairs to persist in the absence of external influences d. the effect of transfer of energy from one object striking another resulting in a near-instant change of relative velocity

Answers

Gravity can best be described as A: "the tendency of masses to move towards each other".

Gravity is the force through which a planet or any other body draws objects toward its center. Gravity keeps all planets in an orbit around the sun. It means that gravity is a force of attraction between objects or bodies that occurs because of their mass. Gravity becomes stronger as mass is increased, and it becomes weaker as the distance between the objects is increased.

Thus, gravity is best defined as the tendency of masses of objects that keeps them moving toward each other.

You can learn more about gravity at

https://brainly.com/question/940770

#SPJ4

how long will a bus take to travel 150 km at an average speed of 40km/h answer

Answers

The actual answer is 3.75

Joe pushes a 12,000 N car, starting from rest, with a force of 310 N for 20 seconds. (a) What is the magnitude of the car's acceleration? (b) How much force would be needed to stop the car in a distance of 30 m?

Answers

The acceleration of the car can be obtained as  0.26 m/s^2. The force required to ove it a distance of 30 m is 11760 N.

What is the acceleration?

We know that the acceleration is the change in the velocity of the object with time. Now we know from the Newton law that the force is the product of the mass of the object and the acceleration.

Now we have that;

weight = mass * acceleration due to gravity

mass = weight/ acceleration due to gravity

mass = 12,000 N / 10 m/s^2

= 1200 Kg

The we know that;

Force = mass * acceleration

acceleration = Force/mass

=  310 N/1200 Kg

= 0.26 m/s^2

For the force that that is needed to move the car a distance of 30 m we have;

F = ma

= 1200 Kg * 9.8 m/s^2

= 11760 N

This is the force that ca move the object forward.

Learn more about distance:https://brainly.com/question/13034462

#SPJ1

How would newton law of motion relate to the movement of bumper car how might the ma of the rider and the peed of the car affect thi movement

Answers

According to the Newtons third law of motion, the collision between the bumper car and the rider will affect both of them as both the systems have mass and are moving with certain velocities.

Collision is a case where one moving object or person violently collides with another.

The law of interaction or the Newton's third law of motion, says that if one body exerts a force on a second body, the second body exerts a force equal in magnitude and opposite in direction on the first body.

It's the law of action-reaction, and it helps to explain why you feel a jolt when you collide with another bumper car.

As we know momentum is P = m*v i.e. momentum (P) is directly proportional to the mass and velocity.

Heavier bodies have more mass, therefore have more momentum.

here, the bumper car is the heavy system and hence, it will exerts more impact on the rider.

To know more about collision,

https://brainly.com/question/7593984

#SPJ4

which is the correct answer

Answers

it stop flies from sitting on the food

box is moving at a constant velocity static friction is 0.35 what does it take to accelate it at 1.2

Answers

If the net force on an object is zero, it will slide down an inclined plane at a constant velocity. This knowledge can be used to calculate the coefficient of kinetic friction between two objects.

The kinetic friction on a slope is denoted as f k = k m g cos. The change in velocity (v) over the change in time (t) is expressed by the equation a = v/t. This enables you to calculate how quickly velocity varies in meters per second squared (m/s2). The coefficient of friction (fr) is a quantity that represents the ratio of the frictional resistive force (Fr) divided by the normal or perpendicular force (N) pushing the objects together.

Learn more about velocity here-

https://brainly.com/question/18084516

#SPJ4

Track Block A student must determine the inertial mass of a block attained to a horizontal track. The block is free to move horizontally along the track, as shown above, Frictional forces are considered to be negligible. The student may only choose two measuring tools to determine the inertial mass of the block. What tools should the student choose? Select two answers.
a. Stopwatch
b. Accelerometer
с. Force sensor
d. Meterstick

Answers

The student should choose accelerometer and force sensor for the determination of the inertial mass of the block.

Inertia can be define as the tendency of an object to resist acceleration or we can say tendency of an object to change its state of motion. Inertial Mass is therefore a measure of an object's inertia.

We can also say that inertial mass measures the tendency to resist change in state of motion. The more mass of an object means, the more it resists acceleration. So, it has more inertia.

An accelerometer is an electronic sensor to measure the acceleration forces on an object. It is used to determine the object’s position in space and also to monitor the object’s movement.

A Force Sensor is a transducer to convert an input mechanical load, weight, tension, compression or pressure into an electrical output signal.

To know more about force sensor here

brainly.com/question/28906632

#SPJ4

the gas undergoes an isothermal compression from point 2 until the volume is restored to the value it had at point 1. what is the final pressure of the gas? express your answer to two significant figures and include the appropriate units.

Answers

The final pressure of the gas is 3atm.

As given in the question,

The volume of the gas at point 1  ( [tex]V_1[/tex]) is 1000 [tex]cm^3[/tex]

The volume of the gas at point 2 ( [tex]V_2[/tex]) is 3000[tex]cm^3[/tex]

The pressure of the gas ([tex]P_2[/tex]) is 1 atm

For an isothermal process , the temperature of the system remains constant so,

The formula to find the pressure of the gas is

   [tex]P_1V_1=P_2V_2[/tex]                                                                      ----(1)

Where

[tex]V_1[/tex] is the volume of the gas at point 1

[tex]V_2[/tex] is the volume of the gas at point 2

[tex]P_1[/tex] is the pressure of the gas at point 1

[tex]P_2[/tex] is the pressure of the gas at point2

now substitute the values given in the question in the equation (1),

[tex]P_1V_1=P_2V_2\\P_1 =\frac{ P_2V_2}{V_1}[/tex]

=>[tex]P_1[/tex] = [tex]\frac{1\times 3\times10^{-3} }{1\times 10^{-3} }[/tex]

=> [tex]P_1[/tex] = 3

Pressure is 3 atm

To learn more about Isothermal compression:

https://brainly.com/question/27476852

#SPJ4

When an object is moving with uniform circular motion, the object’s tangential speed?

Answers

Answer:

is constant

Explanation:

When an object is moving with uniform circular motion, the object’s tangential speed is constant.

Which of the following definitions best describes the concept of work?(a) the flow of energy from one object or substance to another due to a difference in temperature.(b) the flow of energy from one body to another through uniform molecular motion.(c) the force associated with molecular motion.(d) the random motion of molecules in a gas at low pressure.

Answers

Answer:

Your answer is (c) the force associated with molecular motion

Explanation:

Hope this helps :D

20 points, will give brainliest.
If 37 newtons of force is applied to the object pictured above with 6 newtons of friction...

Answers

Answer: 31 N

Explanation:

Forces in the y-direction (Fn and Fg) are balanced. (ΣFy = 0)

ΣFx = Fa- Ff = 37N - 6N = 31N

A 0.290-mm-diameter silver wire carries a 40.0 mA current. What is the electric field in the wire? Express your answer with the appropriate units. What is the electron drift speed in the wire? Express your answer with the appropriate units.

Answers

Answer:

E = 0.0096 N/C

Explanation:

E = I/σπr²

I = 40 mA = 0.04A

σ silver = 6.29X10⁷ /Ωm

r = 0.29 mm/2 = 0.145 mm = 1.45x10⁻⁴ m

E = 0.04A / (6.29X10⁷ /Ωm)(π)(1.45x10⁻⁴ m)² = 0.0096 N/C

*sorry, don't have time to calculate electron drift velocity for you!

How do you calculate the number of ejected electrons?

Answers

The number of ejected electrons in a photoelectric effect experiment can be calculated using the following formula:

What are electrons?

An electron is a subatomic particle that has a negative electric charge. It is one of the fundamental building blocks of matter, along with the proton and neutron. Electrons are found in the outermost region of an atom, called the electron cloud or electron shell.

number of ejected electrons = intensity of light * time of exposure

where intensity of light is the intensity of the light beam (usually measured in watts per square meter), and time of exposure is the length of time that the light beam is shone on the metal surface.

Alternatively, the number of ejected electrons can be calculated using the following formula:

number of ejected electrons = current * time of exposure

where current is the current flowing through the circuit (usually measured in amperes), and time of exposure is the length of time that the light beam is shone on the metal surface.

Therefore, the number of ejected electrons is proportional to the intensity of the light beam and the length of time that it is shone on the metal surface.

To learn more about electrons from the given link:

https://brainly.com/question/26084288

#SPJ4

an automobile horn emits a sound frequency of 800 hzas measured by a stationary observer. what frequency would be measured by an observer moving toward the source at 35:0 m

Answers

Answer:

The source emits sound at 800 / sec -        f = 800 / s

The auto moves at 35 / 800 sec (the apparent wavelength is shortened)

f' = f + f vo / v       where vo is the speed of the observer

f' = f (v + vo) / v        rewriting the above equation

f' = 800 / sec (331 + 35) / 331       using 331 m/s as the speed of sound

f' = 885 / sec          sound heard      

a small 1.4 n stone slides down a frictionless bowl, starting from rest at the rim. how hard is the bowl pushing on it

Answers

The force that the bowl is exerting on a small 1.4 n stone as it slides down is 13.72 n.

To determine the force that the bowl is exerting on the stone as it slides down, you will need to consider the stone's mass, the acceleration of the stone, and Newton's second law of motion.

Newton's second law of motion states that the force acting on an object is equal to the mass of the object times its acceleration. This can be written as:

F = m * a

where F is the force acting on the object, m is the mass of the object, and a is the acceleration of the object.

In this case, the mass of the stone is given as 1.4 n, and the acceleration of the stone is the acceleration due to gravity, which is 9.8 m/s^2.

Plugging in the values, you get:

F = 1.4 n * 9.8 m/s^2

F = 13.72 n

To know more about motion

https://brainly.com/question/13966796

#SPJ4

What are the 10 examples of force?

Answers

Answer:

1.Opening and shutting a door

2.Squeezing water out of wet clothes

3.Punching a pillow

4.Stomping your foot

5.Pushing a manual mower

6.Ripping a piece of paper

7.Crushing a ball of dough

8.Pulling out an ingrown hair from your leg

9.Pulling a light chain

10.Smacking a horses butt to signal it to "GIDDIE UP!"

Explanation:

Other Questions
Is this a function? please explain if possible. PLEASE HELP ASAPWhat negative consequence can occur when non-native species are introduced into an ecosystem? Native species will prey on the invasive species. The introduced species prey on native species. The introduced species mate with native species, adding genetic variety. The introduced species strengthen the ecosystem by adding diversity. A sample of unknown gas has a temperature of 378k. When the temperature is increased to 546k,the volume also increases to 1047 ml. What was the original volume ? Which of the following best describes the changing attitudes throughout the 1960s?A. Relaxing social and sexual normsB. Total social and racial inclusionC. Outward conservativism, but inward liberalismD. A shift toward conservatism What is a bright streak of light that results from a space rock burning in earths atmosphere? A. Meteor B. Asteroid C. Meteorite D. Meteoroid Anne surveyed the 12 slowest runners in PE, class about their favorite sports,Is this sample of the students in the PE, class likely to be biased? What is the product? Find the indicated side of theright triangle60730X== [?] ) What is the goal of segregation?O A. To encourage the integration of public facilitiesB. To help people in need of assistancec. To separate racial groupsD. To maintain a democratic system which graph represents the function f(x) = 4|x|? who ever gets this will get a brainlest help................ what is the value of log39? f(x) = cos(x - 90)Which is the value of f(0)?A 1B 0C-112 What were the positive and negative affects of Hamilton's financial plan? does our money express according to the documentary Cause/Effect The Lighting Thief Ch. 8 Match each cause with its effectHELP ASAP I WILL GIVE BRAINILEST AND EXTRA POINTS please no links i dont have time for that lol Careful studies have shown that robin eggs of intermediate size are more likely to produce viable offspring than smaller or larger eggs. This is anexample ofGenetic driftStabilizing selectionHeterozygote advantage.Directional selection From the lists of things the president can and cannot do, what do you infer about the president's life? Answera The president must follow the rules and be able to compromise to accomplish his goals. b The president feels like the most important person in America. c The president is always busy. d The president needs a lot of help. Please help with this science assignment