Mary is trying to pull Julie on a sled across a flat snowy field. Mary pulls on the rope attached to the sled. Her pulling force is directed horizontally. Julie weighs 109 pounds. The sled weights 12 pounds. If the coefficient of static friction between the sled runners and the snow is 0.42, how much force must Mary pull with (in lbs) to start moving the sled

1. measure of how quickly velocity is changing . . . acceleration

2. speed in a given direction . . . velocity

3. force that resists moving one object against another . . . friction

4. measure of the pull of gravity on an object . . . weight

5. tendency of an object to resist a change in motion . . . inertia

6. size . . . magnitude

1. measure of how quickly velocity is changing is acceleration.

2. speed in a given direction is velocity.

3. force that resists moving one object against another is friction.

4. measure of the pull of gravity on an object is weight.

5. tendency of an object to resist a change in motion is inertia.

Acceleration has the term used in mechanics to describe the pace at which the velocity of an object varies over time. Acceleration is a vector quantity (in that they have magnitude and direction). The direction of an object's acceleration is determined by the direction of the net force acting on it.

It is a vector quantity with an SI unit is m/s² and the dimension formula is LT⁻². A massive body will accelerate or alter its velocity at a constant rate when a constant force is applied to it, according to Newton's second law. In the simplest case, when a force is applied to an object at rest, it accelerates in the force's direction.

Therefore, 1. measure of how quickly velocity is changing is acceleration.

2. speed in a given direction is velocity.

3. force that resists moving one object against another is friction.

4. measure of the pull of gravity on an object is weight.

5. tendency of an object to resist a change in motion is inertia.

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Answer:

Distance, S = 130m

Explanation:

Given the following data;

Initial velocity = 2m/s

Final velocity = 28m/s

Acceleration = 3m/s²

To find the distance, we would use the third equation of motion.

V² = U² + 2aS

Substituting into the equation, we have;

28² = 2² + 2*3*S

784 = 4 + 6S

6S = 784 - 4

6S = 780

S = 780/6

Distance, S = 130m

Answer:

45 s .

Explanation:

The accelerator will first accelerate , then move with uniform velocity and at last it will decelerate to rest .

displacement s = ?

acceleration a = 1 m /s²

Final speed v = 5 m/s

initial speed u = 0

v² = u² + 2as

5² = 0 + 2 x 1 x s

s = 12.5  m

B)  Let time of acceleration or deceleration be t

v = u + a t

5 = 0 + 1 t

t = 5 s

Similarly displacement during deceleration = 12.5 m

Total distance during uniform motion = 200 - ( 12.5 + 12.5 ) =  175 m .

velocity of uniform motion = 5 m /s

time during which there was uniform velocity = 175 / 5 = 35 s

Total time = 5 + 35 + 5 = 45 s .

Answer:

If the force goes in the direction of movement, the speed must increase and if the net force goes in the opposite direction, the speed must decrease.

Explanation:

The principle of inertia or Newton's first law states that every body remains static or with constant velocity if there is no net force acting on it.

Based on this principle, if we have a net force, the velocity of the body changes by having an unbalanced force acting.

If the force goes in the direction of movement, the speed must increase and if the net force goes in the opposite direction, the speed must decrease.

Answer:

1470J

Explanation:

Given parameters:

Mass of the person  = 50kg

height  = 3m

Unknown:

Work done  = ?

Solution:

To solve this problem, we use the expression below:

     Work done  = mass x acceleration due gravity x height

So;

     Work done  = 50 x 9.8 x 3 = 1470J

Answer:

Explanation:

Speed of sound = 331 m /s

speed of jet = 7 .00 Mach = 7 times speed of sound

= 7 x 331 = 2317 m /s

distance to be covered = 5000 x 1000 = 5 x 10⁶ m

Time taken = distance / speed of jet

= 5 x 10⁶ / 2317

= 2.158 x 10³ s

= 35.96 minutes .

The sky changes colors at sunset because the atmosphere ABSORBS some colors of light more than other colors.

The second choice ("The atmosphere bends light") is a correct statement, but it's not the reason that the sky changes colors at sunset.

Answer:

The atmosphere bends light.

Explanation:

I got the test, and passed! =)

Answer:

* he new moon phase when the position is       Sun - Moon - Earth,

* have of the Full Moon when the position is     Sun - Earth - Moon,

*All the phases of the moon are governed by the movement of the Moon around the Earth.

Explanation:

In the solar system, the planets revolve around the sun, which is much more massive, in the case of the Earth it is more massive than its satellite, therefore the Moon revolves around the Earth in a period of approximately 28 days.

It is said that the moon is in the new moon phase when the position is Sun - Moon - Earth, so the moon cannot be seen

It is in the phase of the Full Moon when the position is

                  Sun - Earth - Moon, in this case the moon can be observed by the light reflected from it.

All the phases of the moon are governed by the movement of the Moon around the Earth.

Answer:

hello your question is not properly arranged attached below is the arranged table and solution

answer : attached table below

Explanation:

Given data:

02 molecules size = 10^-10m

smoke particles size = 0.3 mm

cloud droplets size = 20 mm

Rain droplets size = 3 mm

Attached below is a table showing the kind of scattering that is expected to occur at various wave lengths

Note : For Rayleigh scattering the wave particle is smaller than the wave length while for Non-selective scattering the wave particle is greater than the wavelength.

and  For Mie scattering the wavelength is the same as the wavelength.

Answer:

40J

Explanation:

Given parameters:

Mass of box  = 10kg

distance moved  = 2m

Force applied  = 20N

Unknown:

Work done in pushing the box  = ?

Solution:

The work done in moving a body is a function of the force applied to move it through a particular distance.

 Work done  = Force x distance

So;

   Work done  = 20 x 2  = 40J

Answer:

Explanation:

To find the angular velocity of the tank at which the bottom of the tank is exposed

From the information given:

At rest, the initial volume of the tank is:

[tex]V_i = \pi R^2 h_i --- (1)[/tex]

where;

height h which is the height for the free surface in a rotating tank is expressed as:

[tex]h = \dfrac{\omega^2 r^2}{2g} + C[/tex]

at the bottom surface of the tank;

r = 0, h = 0

∴

[tex]h = \dfrac{\omega^2 r^2}{2g} + C[/tex]

0 = 0 + C

C = 0

Thus; the free surface height in a rotating tank is:

[tex]h=\dfrac{\omega^2 r^2}{2g} --- (2)[/tex]

Now; the volume of the water when the tank is rotating is:

dV = 2π × r × h × dr

Taking the integral on both sides;

[tex]\int \limits ^{V_f}_{0} \ dV = \int \limits ^R_0 \times 2 \pi \times r \times h \ dr[/tex]

replacing the value of h in equation (2); we have:

[tex]V_f} = \int \limits ^R_0 \times 2 \pi \times r \times ( \dfrac{\omega ^2 r^2}{2g} ) \ dr[/tex]

[tex]V_f = \dfrac{ \pi \omega ^2}{g} \int \limits ^R_0 \ r^3 \ dr[/tex]

[tex]V_f = \dfrac{ \pi \omega ^2}{g} \Big [ \dfrac{r^4}{4} \Big]^R_0[/tex]

[tex]V_f = \dfrac{ \pi \omega ^2}{g} \Big [ \dfrac{R^4}{4} \Big] --- (3)[/tex]

Since the volume of the water when it is at rest and when the angular speed rotates at an angular speed is equal.

Then [tex]V_f = V_i[/tex]

Replacing equation (1) and (3)

[tex]\dfrac{\pi \omega^2}{g}( \dfrac{R^4}{4}) = \pi R^2 h_i[/tex]

[tex]\omega^2 = \dfrac{4g \times h_i }{R^2}[/tex]

[tex]\omega =\sqrt{ \dfrac{4g \times h_i }{R^2}}[/tex]

[tex]\omega = \sqrt{\dfrac{4 \times 9.81 \ m/s^2 \times 0.7 \ m}{(0.5)^2} }[/tex]

[tex]\omega = \sqrt{109.87 }[/tex]

[tex]\mathbf{\omega = 10.48 \ rad/s}[/tex]

Finally, the angular velocity of the tank at which the bottom of the tank is exposed  = 10.48 rad/s

Answer:

D- Repulsion

Explanation:

A positively charged object will exert a repulsive force upon a second positively charged object.

Answer:

A. Gamma decay

Explanation:

A form of nuclear decay in which the atomic number is unchanged is a gamma decay.

The atom has undergone a gamma decay.

In a gamma decay, no changes occur to the mass and atomic number of the substance.

Answer:

The formula of nitrogen trifluoride is NF 3

The formula of ammonia is NH3

The formula of magnesium hydroxide is Mg(OH)2

Explanation:

The formula of a compound refers to the correct representation of the compound using appropriate chemical symbols.

The formula of a compound is derived from the symbols of its constituent elements. The formula of the compound must correctly show the number of atoms of each element in one formula unit of the compound.

In the answer section, the correct names or formulas of some compounds have been shown

Answer:

A. The formula of nitrogen trifluoride is NF3.

B. The formula of ammonia is NH3.

D. The formula of calcium chloride is CaCI2.

H. The formula of magnesium hydroxide is Mg(OH)2.

Explanation:

Answer:

Hi lol

Explanation:

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Answer:

mechanical energy

Explanation:

when raised up has potential energy

Answer:

potential energy

Explanation:

potential energy

to plow fields beacuse it's much easier to plow on tractor than on foot

Answer:

the work required to stretch the spring is 8 J.

Explanation:

Given;

spring constant, k = 2500 N/m

extension of the spring, x = 8 cm = 0.08 m

The work required to stretch the spring is calculated as;

[tex]W = \frac{1}{2} kx^2\\\\W = \frac{1}{2} \times 2500 \times 0.08^2\\\\W = 8 \ J[/tex]

Therefore, the work required to stretch the spring is 8 J.

Answer:

True

Explanation:

Objects have the same velocity only if they are moving at the same speed and in the same direction.

Answer:

The process of distillation begins with heating a liquid to boiling point. The liquid evaporates, forming a vapor. The vapor is then cooled, usually by passing it through pipes or tubes at a lower temperature. The cooled vapor then condenses, forming a distillate

I hope it helps mate

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Answer:

0.000153DaL  

Explanation:

We have been given:

         15.3mL to convert to DaL

DaL is a unit of volume which indicates a decaliter.

 This implies that;

             1 Da L  = 1 x 10²L

So:

               1 mL  = 1 x 10⁻³L

       So 15.3mL will give 15.3 x 10⁻³L

So;

           1 x 10²L   =  1 DaL  

      15.3 x 10⁻³L  will give [tex]\frac{15.3 x 10^{-3} }{1 x 10^{2} }[/tex]   = 15.3 x 10⁻⁵DaL

Therefore, this is 0.000153DaL  

Answer:

The 59th element is Praseodymium it's symbol is Pr.

Answer:

See the explanation below.

Explanation:

Energy is the ability of bodies to perform work and produce changes in themselves or other bodies.

There are several types of energy, but let's talk specifically about mechanical energy.

Mechanical energy is associated or subdivided into kinetic, potential, and elastic energies.

Kinetic energy

[tex]E_{kin}=\frac{1}{2}*m*v^{2}[/tex]

Potential energy

[tex]E_{pot}=m*g*h[/tex]

Elastic Energy

[tex]E_{elas}=\frac{1}{2} *k*x^{2}[/tex]

Answer:

108J

Explanation:

Given parameters:

Mass the body  = 1.5kg

Impulse  = 6kgm/s

Initial velocity  = 0m/s

Unknown:

Kinetic energy of the body  = ?

Solution:

The kinetic energy of a body is the energy due to the motion of the body.

To solve this problem, we use the expression below:

   K.E = [tex]\frac{1}{2}[/tex] m (V - U)²  

m is the mass

V is the final velocity

U is the initial velocity

 From;

     Impulse  = m V

      6   = 1.5 x V

       V  = [tex]\frac{6}{1.5}[/tex]    = 4m/s

So;

 K.E  =  [tex]\frac{1}{2}[/tex]  x 6 x (6  - 0)²    = 108J

Answer:

Explanation:

The formula holding the relationship between wavelength and frequency of a wave can be expressed as:

[tex]\lambda = \dfrac{v}{f}[/tex]

where;

[tex]\lambda =[/tex] wavelength

v = speed

f = frequency

Given that:

v = 192 m/s and f = 240Hz

Then;

[tex]\lambda = \dfrac{192 \ m/s}{240 \ Hz}[/tex]

[tex]\lambda = 0.800 \ m[/tex]

Now, to estimate the respective amplitude of the string, we need to approach it by using the concept of wave equation which is:

y = A sin kx

here;

A = amplitude of the standing wave

k = wave number

x = maximum displacement

y = distance from center

recall that:

[tex]k = \dfrac{2 \pi}{\lambda}[/tex]

∴

[tex]y = A sin \dfrac{2 \pi}{\lambda }x[/tex]

Now;

for A = 0.400 cm ; [tex]\lambda[/tex] = 0.800 m ; k = 40 cm

Then;

[tex]y =(0.400 \ cm ) \ sin \dfrac{2 \pi}{0.800 m }\times (40 \ cm \times \dfrac{10^{-2} \ m}{1 \ cm } )[/tex]

y = 0.400 sin π

y = 0 cm

At distance 40 cm; the amplitude = 0 cm

Thus, it is a node.

For k = 20cm

Then:

[tex]y =(0.400 \ cm ) \ sin \dfrac{2 \pi}{0.800 m }\times (20 \ cm \times \dfrac{10^{-2} \ m}{1 \ cm } )[/tex]

y = 0.400 sin π/2

y = 0.400 cm

At distance 20 cm; the amplitude = 0.400 cm

Thus, it is antinode.

For k = 10cm

Then:

[tex]y =(0.400 \ cm ) \ sin \dfrac{2 \pi}{0.800 m }\times (10 \ cm \times \dfrac{10^{-2} \ m}{1 \ cm } )[/tex]

4y = 0.400 sin π/2

y = 0.283 cm

At distance 10 cm; the amplitude = 0.283 cm

b)

The required time taken to go through the displacement( i.e. from largest upward to downward) is the time required to cover half of the wavelength.

This is expressed as:

[tex]T = \dfrac{1}{2} \times \dfrac{1}{f}[/tex]

[tex]T= \dfrac{1}{2} \times \dfrac{1}{240 \ Hz}[/tex]

T = 0.00208

T = 2.08 × 10⁻³ s

Answer:

39.26 s

Explanation:

From the question given above, the following data were obtainedb

Initial velocity (u) = 6 m/s

Acceleration (a) = 1.9 m/s²

Distance travelled (s) = 1700 m

Time (t) =?

Next, we shall determine the final velocity of the plane. This can be obtained as follow:

Initial velocity (u) = 6 m/s

Acceleration (a) = 1.9 m/s²

Distance travelled (s) = 1700 m

Final velocity (v) =?

v² = u² + 2as

v² = 6² + (2 × 1.9 × 1700)

v² = 36 + 6460

v² = 6496

Take the square root of both side

v = √6496

v = 80.6 m/s

Finally, we shall determine the time taken before the plane lifts off. This can be obtained as follow:

Initial velocity (u) = 6 m/s

Acceleration (a) = 1.9 m/s²

Final velocity (v) = 80.6 m/s

Time (t) =?

v = u + at

80.6 = 6 + 1.9t

Collect like terms

80.6 – 6 = 1.9t

74.6 = 1.9t

Divide both side by 1.9

t = 74.6 / 1.9

t = 39.26 s

This, it will take 39.26 s before the plane lifts off.

Answer:

we all know that deforestation is when tress are cut down but this may cause cardio dioxide to go up into the atmosphere and this may cause the rise in sea level and temperates tend to fluctuate

Explanation:

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