Answer:
The weight of the girl is 250 N
Explanation:
Static Equilibrium
Static equilibrium occurs when an object is at rest, i.e., neither rotating nor translating.
In the static rotational equilibrium, the total torque is zero with respect to any rotational axis.
The torque applied by a force F perpendicular to a displacement X with respect to a reference rotating point is:
T = F*X
The seesaw will be in rotational equilibrium if the torque applied by the boy of mass m1=40 Kg at x1=2 m from the pivot is equal to the torque applied by the girl of unknown mass m2 at x2=3.2 m from the pivot.
The force applied by both children is their weight:
[tex]F_1 = W_1 = m_1g[/tex]
[tex]F_2 = W_2 = m_2g[/tex]
It must be satisfied:
[tex]m_1gx_1=m_2gx_2[/tex]
Simplifying:
[tex]m_1x_1=m_2x_2[/tex]
Solving for m2:
[tex]\displaystyle m_2=\frac{m_1x_1}{x_2}[/tex]
[tex]\displaystyle m_2=\frac{40*2}{3.2}[/tex]
[tex]m_2=25\ kg[/tex]
Her weight is:
[tex]\mathbf{W_2=25*10 = 250\ N}[/tex]
The weight of the girl is 250 N
Suppose it takes a constant force a time of 6.0 seconds to slow a 2500 kg truck
from 26.0 m/sec to 18.0 m/sec. What is the magnitude of the force? Give
your answer in scientific notation rounded correctly.
Answer:
[tex]3.3\cdot 10^3\:\mathrm{N}[/tex]
Explanation:
Impulse on an object is given by [tex]\mathrm{[impulse]}=F\Delta t[/tex].
However, it's also given as change in momentum (impulse-momentum theorem).
Therefore, we can set the change in momentum equal to the former formula for impulse:
[tex]\Delta p=F\Delta t[/tex].
Momentum is given by [tex]p=mv[/tex]. Because the truck's mass is maintained, only it's velocity is changing. Since the truck is being slowed from 26.0 m/s to 18.0 m/s, it's change in velocity is 8.0 m/s. Therefore, it's change in momentum is:
[tex]p=2500\cdot 8.0=20,000\:\mathrm{kg\cdot m/s}[/tex].
Now we plug in our values and solve:
[tex]\Delta p=F\Delta t,\\F=\frac{\Delta p}{\Delta t},\\F=\frac{20,000}{6}=\fbox{$3.3\cdot 10^3\:\mathrm{N}$}[/tex](two significant figures).
A bicycle racer rides from a starting marker to a turnaround marker at 10 m/s. She then rides back along the same route from the turnaround marker to the starting marker at 16 m/s. What is her average speed for the whole race?
Answer:
12.31 m/s
Explanation:
If we recall from the previous knowledge we had about speed,
we will know that:
speed = distance/ time.
As such:
The average speed of the rider bicycle is
average speed = total distance/ total time
Mathematically, it can be computed as:
[tex]v_{avg} = \dfrac{d+d}{\dfrac{d}{v_1}+ \dfrac{d}{v_2}}[/tex]
[tex]v_{avg} = \dfrac{2d}{\dfrac{d}{10 \ m/s}+ \dfrac{d}{16 \ m/s}}[/tex]
[tex]v_{avg} = \dfrac{2}{\dfrac{1}{10 \ m/s}+ \dfrac{1}{16 \ m/s}}[/tex]
[tex]v_{avg} = \dfrac{2}{\dfrac{13}{80 \ m/s}}[/tex]
[tex]\mathbf{v_{avg} =12.31 \ m/s}[/tex]
Each spring, a crevice in the cliff wall widens and deepens. What is the best explanation for how physical weathering causes the crevice to widen and deepen?
Winds deposit sand into the crevice.
Water freezes and expands in the crevice.
Snow melts and evaporates between the rocks in the crevice.
Air pollution in the area causes a reaction that widens the crevice.
Answer: water freezes and expands in the crevice
Explanation:
Answer:
Water freezes and expands in the crevice
Explanation:
What is one characteristic of an electron?
Answer:
A is the best character that defines an electron.
If an object has applied force of 20 N and a frictional force of 5 N what is the net force?
Answer:
Net force = 15 N
Explanation:
Given that,
Applied force on an object = 20 N
Frictional force = 5 N
We need to find the net force acting on the object.
Friction is an opposing force. It acts in the opposite direction.
Net force = Applied force - Frictional force
= 20 N - 5 N
= 15 N
Hence, the net force acting on the object is 15 N.
A string with a mass density of 3 * 10^-3 kg/m is under a tension of 380 N and is fixed at both ends. One of its resonance frequencies is 195 Hz. The next higher resonance frequency is 260 Hz.
Required:
a. What is the fundamental frequency of this string?
b. Which harmonics have the given frequencies?
c. What is the length of the string?
Answer:
(a) the fundamental frequency of this string is 65 Hz
(b) the harmonics of the given frequencies are third and fourth respectively.
(c) the length of the string is 2.74 m
Explanation:
Given;
mass density of the string, μ = 3 x 10⁻³ kg/m
tension of the string, T = 380 N
resonating frequencies, 195 Hz and 260 N
For the given resonant frequencies;
[tex]195 = \frac{n}{2l} \sqrt{\frac{T}{\mu} } ---(1)\\\\260 = \frac{n+1}{2l} \sqrt{\frac{T}{\mu} } ---(2)\\\\divide \ (2) \ by (1)\\\\\frac{260}{195} = \frac{n+1 }{n} \\\\260n = 195(n+1)\\\\260 n = 195 n + 195\\\\260n - 195n = 195\\\\65n = 195\\\\n = \frac{195}{65} \\\\n = 3[/tex]
(c) From any of the equations, solve for Length of the string (L);
[tex]195 = \frac{n}{2l} \sqrt{\frac{T}{\mu} } \\\\195 = \frac{3}{2l}\sqrt{\frac{380}{3\times 10^{-3}} } \\\\l = \frac{3}{2\times 195}\sqrt{\frac{380}{3\times 10^{-3}} }\\\\l = 2.74 \ m[/tex]
(a) the fundamental frequency is calculated as;
[tex]f_o = \frac{1}{2l} \sqrt{\frac{T}{\mu} } \\\\f_o = \frac{1}{2\times 2.74} \sqrt{\frac{380}{3\times 10^{-3} } }\\\\f_o = 65 \ Hz[/tex]
(b) harmonics of the given frequencies;
the first harmonic (n = 1) = f₀ = 65 Hz
the second harmonic (n = 2) = 2f₀ = 130 Hz
the third harmonic (n = 3) = 3f₀ = 195 Hz
the fourth harmonic (n = 4) = 4f₀ = 260 Hz
Thus, the harmonics of the given frequencies are third and fourth respectively.
Which of these objects are constantly in motion? Select all that apply.
A.
Earth
B.
Planes
C.
Trains
D.
Blood
E.
Sun
F.
Cars
The object Earth, Sun, and Blood are constantly in motion. The correct option is A, D, and E.
What is motion?if a body changes its position with respect to its surroundings in a given interval of time, Then the body is said to be in motion
.
Motion is generally classified as follows.:
i) Rectilinear motion.
ii) Circular motion.
iii) Rotational motion.
iv) Periodic motion.
The Earth is continuously in motion because it continuously revolves around The Sun in an elliptical orbit, due to which a year is 365 days. and also The earth rotates about its own axis once a day.
The Sun also revolves around the galactic center of our Milkyway galaxy. and it also rotates about its own axis continuously. so that the sun is also continuously in motion.
The Human blood is continuously in motion Because our blood is continuously circulating whole over the body with the help of our heart. The heart continuously pumps our blood and circulates it inside the human body.
Hence the Earth, Sun, and blood are continuously in motion.
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The earth rotates through one complete revolution every 1,440 minutes. Since the axis of rotation is perpendicular to the equator, you can think of a person standing on the equator as standing on the edge of a disc that is rotating through one complete revolution every 1440 minutes. Find the angular velocity of a person standing on the equator.
Answer:
The angular velocity of a person standing on the equator is approximately [tex]7.272\times 10^{-5}[/tex] radians per second.
Explanation:
The Earth rotates at constant speed. From Rotational Physics, the angular velocity ([tex]\omega[/tex]), measured in radians per second, is defined by the following formula:
[tex]\omega = \frac{2\pi}{T}[/tex] (1)
Where [tex]T[/tex] is the period of rotation of the Earth, measured in seconds.
If we know that [tex]T = 86400\,s[/tex], then the angular velocity of a person standing on the equator is:
[tex]\omega = \frac{2\pi}{86400\,s}[/tex]
[tex]\omega \approx 7.272\times 10^{-5}\,\frac{rad}{s}[/tex]
The angular velocity of a person standing on the equator is approximately [tex]7.272\times 10^{-5}[/tex] radians per second.
A beaker with water resting on a scale weighs 40 N. A block
suspended on a hanging spring weighs 20 N. The spring scale
reads 15 N when a block is fully submerged in the water. What is
the reading of a scale on which the beaker with water rests, while
the block is submerged in the water after detached from the
hanging spring?
A. 25 N B. 60 N C. 55 N D. 45 N
Answer:
D. 45 N
Explanation:
The weight of the block is 20 N, when the block is fully immerged in water, it weighs 15 N. Hence the loss of weight = 20 N - 15 N = 5 N.
The loss of weight is as a result of the buoyant force. The buoyant force is the upward force exerted by a fluid when an object is fully or partially immersed in a fluid.
The buoyant force of 5 N acts in the upward direction, the weight of the beaker that would be read by the scale when the beaker is immersed in water = 40 N + 5 N = 45 N
Heat traveling through a pan to warm food in the pan is an example of what kind of heat transfer?
A. Convection
B. Radiation
C. Insulation
D. conduction
Answer:
A
Explanation:
Answer:
D. Conduction
Explanation:
Convection heat transfer occurs in fluids, while conduction heat transfer occurs in solids.
A protein molecule in an electrophoresis gel has a negative charge. The exact charge depends on the pHpH of the solution, but 30 excess electrons is typical. What is the magnitude of the electric forceon a protein with this charge in a 1500 N/C electric field?
Answer:
The magnitude of the force = 7.2 × 10⁻¹⁵ C
Explanation:
The total quantization of charge q on an electron = n × e
where;
n = 30
e = 1.6 × 10⁻¹⁸ C
q = 30 × 1.6 × 10⁻¹⁸ C
q = 4.8 × 10⁻¹⁸ C
Now, the magnitude of the force is determined by using the formula:
F = qE
F = ( 4.8 × 10⁻¹⁸ C) ( 1500 N/C)
F = 7.2 × 10⁻¹⁵ C
Q1. A man wants to install a surveillance mirror in his shop, which mirror should he use?(1)
a) Convex mirror
b) Concave mirror
c) Plane mirror
d) Both (a) and (b)
answer is convex mirror
Explanation:
A
Because convex mirror will provide maximum view
a) A bus of mass 760 kg requires 120 m to reach certain velocity value Vf. Ignore friction and drag forces and assume the bus engine exerts a constant forward force F. When the bus is towing a 330-kg small car, how long distance needed to reach same Vf? b) If the Vf of the bus is 28 m/s, what is the tension in the tow cable between bus and small car?
Answer:
Given : A bus of mass 760 kg requires 120 m to reach certain velocity value Vf.
the bus engine exerts a constant forward force F.
To Find : When the bus is towing a 330-kg small car, how long distance needed to reach same Vf?
Solution:
V² - U² = 2aS
V = Vf
U = 0
S = 120 m
=> Vf² - 0 = 2a(120)
=> Vf² = 240a
m = 760 kg
Force = F
F = ma
=> F =760 a
=> a = F/760
Vf² = 240F/760
Case 2 :When the bus is towing a 330-kg small car,
m = 760 + 330 = 1090 kg
a = F/1090
Vf² = 2aS
=> 240F/760 = 2 (F/1090) S
=> S = 120 x 1090 /760
=> S = 172.1 m
172.1 m distance needed to reach same Vf
Explanation:
Surface water is replaced by the blank cycle.
Answer: Surface water is replaced by the water cycle.
Explanation: The water cycle is a cycle that describes the movement of water.
Answer:
it is water cycle when it's one of the process occurs and process is precipation this replaces surface water
A racecar makes 24 revolutions around a circular track of radius 2 meters in
162 seconds. Find the racecar's frequency
Answer:
[tex]0.15\: \mathrm{Hz}[/tex]
Explanation:
The frequency is of an object is given by [tex]f=\frac{1}{T}[/tex], where [tex]T[/tex] is the orbital period of the object.
Since the racecar makes 24 revolutions around a circular track in 162 seconds, it will take the racecar [tex]\frac{162}{24}=6.75\:\mathrm{s}[/tex] per revolution.
Therefore, the frequency of the racecar is [tex]\frac{1}{6.75}=\fbox{$0.15\:\mathrm{Hz}$}[/tex] (two significant figures).
The radius of the track is irrelevant in this problem.
A car of weight 6,400 N has four wheels. Each wheel has an area of
80 cm-touching the road. Find the pressure the car puts on the
ground. I
Answer:
80N/cm^2
Explanation:
Given data
A car of weight 6,400N
Area= 80cm^2
The weight is distributed evenly on the 4 wheels
hence 6400/4
=1600 N
We know that
Pressure = force/Area
Pressure= 1600/80
Pressure= 20 N/cm^2
For the four wheels, the pressure is
=20*4
=80N/cm^2
Planet Earth is held in orbit by the sun's gravitational force pulling on the Earth.
Which one of the following statements are true about that gravitational force?
The sun does not have a gravitational force because it is made of gas.
The earth pulls with more force since it is less massive than the sun.
The sun and the earth pull on each other with equal and opposite forces.
The sun pulls with more force since the sun is more massive than the earth.
Answer:
The sun pulls with more force since the sun is more massive than the earth.
Explanation:
That your answer because the Earth is getting pulled by the gravitational pull from the Sun
discuss how devastating a 7.7 - magnitude earthquake is.
Answer:
Explanation:
It’s devastating because when a earthquake is 7.7 magnitude the
how does a battery work?
Answer:
Essentials. A battery is a device that stores chemical energy and converts it to electrical energy. The chemical reactions in a battery involve the flow of electrons from one material (electrode) to another, through an external circuit. The flow of electrons provides an electric current that can be used to do work.
If a woman walks at a speed of 5 miles/hour for 3 hours, she will have walked how many miles?
The distance walked by the woman at the given speed an time, is 15 miles.
What is meant by speed?The speed of an object is defined as the rate of change of the distance travelled by the object.
Here,
Speed with which the woman is walking,
v = 5 miles/hour
Time taken by the woman for walking,
t = 3 hours
We know speed is the rate of change of distance,
v = d/t where d is the distance travelled by the woman
So, d = v x t
d = 5 x 3
d = 15 miles
Hence,
The distance walked by the woman at the given speed an time, is 15 miles.
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In one type of Combustion reaction, _______ is combined with oxygen to create heat and light.
A) nitrogen
B) carbon
C) hydrogen
Answer:
carbon.
Explanation:
the reaction would then create c02 as a product
the earth's moon has a gravitational field strength of about 1.6 n/kg near its surface. the moon has a mass of 7.35x10^22 kg. what is the radius of the moon? please show steps on how to do it please.
Answer:
1750km
Explanation:
How is the Moon thought to have formed
While camping in a tent on a cold night, which would keep you warmer for a longer period of time. a 10 kg
bag of hot iron pellets or a 10 kg bag of hot water at the same temperature? Explain. PLEASE ANSWER
Answer:
a 10 kg bag of hot water at the same temperature
Explanation:
A 10kg bag of hot water at the same temperature will retain heat much better and keep the tent warmer at night compared to the iron pellet.
Water has a very large specific heat capacity. The specific heat capacity of water allows for it to retain heat better. It takes a larger amount of heat to warm water compared to iron which is a better conductor. In like manner, it takes more time for water to lose that amount of heat it has gained by the heating process. This is why it is a better choice to keep the room warmA basketball is picked up off the ground and carried to the top of a platform that is 160 feet up. It is then dropped to the ground. The ball rebounds one-half the height each time it hits the ground. What is the total vertical distance the ball will travel from the moment it is picked up to the moment it reaches its maximum height after the fourth bounce
Answer:
Explanation:
The total distance travelled by ball before first bounce
= 160 + 160 = 320 ft
Distance travelled between first bounce and second bounce
= 80 + 80 = 160 ft
Distance travelled between second bounce and third bounce
= 40 + 40 = 80 ft
Distance travelled between third bounce and fourth bounce
= 20 + 20 = 40 ft .
Distance travelled in fourth bounce = 10 ft
Total distance travelled = 320 + 160 + 80 + 40 + 10
= 610 ft .
You are holding two balloons of the same shape and size. One is filled with helium, and the other is filled with ordinary air. On which balloon the buoyant force is greater?
a. The helium filled balloon experiences the greater buoyant force.
b. The air filled balloon experiences the greater buoyant force.
c. Both balloons experiences same buoyant force.
Answer:
Both balloons experiences same buoyant force.
Explanation:
Buoyant force is defined as the upward force that is exerted on an object which is wholly or partly immersed in a fluid. We can also define it as the upward force exerted by any fluid upon a body immersed in it. We may also refer to this buoyant force as the upthrust.
This buoyant force is the push of air on the balloon and it is independent of the contents of the balloons. Hence, both balloons experiences same buoyant force.
Two point charges have a total electric potential energy of -24 J, and are separated by 29 cm.
If the total charge of the two charges is 45 μC, what is the charge, in μC, on the positive one?
What is the charge, in μC, on the negative one?
Answer:
The charge of the negative one is 13.27 microcoulombs and the positive one has a charge of 58.27 microcoulombs.
Explanation:
Electric potential energy between two point charges is derived from concept of Work, Work-Energy Theorem and Coulomb's Law and described by the following formula:
[tex]U_{e} = \frac{k\cdot q_{A}\cdot q_{B}}{r}[/tex] (1)
Where:
[tex]U_{e}[/tex] - Electric potential energy, measured in joules.
[tex]q_{A}[/tex], [tex]q_{B}[/tex] - Electric charges, measured in coulombs.
[tex]r[/tex] - Distance between charges, measured in meters.
[tex]k[/tex] - Coulomb's constant, measured in kilogram-cubic meters per square second-square coulomb.
If we know that [tex]U_{e} = -24\,J[/tex], [tex]q_{A} = 45\times 10^{-6}\,C+ q_{B}[/tex], [tex]k = 9\times 10^{9}\,\frac{kg\cdot m^{3}}{s^{2}\cdot C^{2}}[/tex] and [tex]r = 0.29\,m[/tex], then the electric charge is:
[tex]-24\,J = -\frac{\left(9\times 10^{9}\,\frac{kg\cdot m^{3}}{s^{2}\cdot C^{2}} \right)\cdot (45\times 10^{-6}\,C+q_{B})\cdot q_{B}}{0.29\,m}[/tex]
[tex]-6.96 = -405000\cdot q_{B}-9\times 10^{9}\cdot q_{B}^{2}[/tex]
[tex]9\times 10^{9}\cdot q_{B}^{2}+405000\cdot q_{B} -6.96 = 0[/tex] (2)
Roots of the polynomial are found by Quadratic Formula:
[tex]q_{B,1} = 1.327\times 10^{-5}\,C[/tex], [tex]q_{B,2} \approx -5.827\times 10^{-5}\,C[/tex]
Only the first roots offer a solution that is physically reasonable. The charge of the negative one is 13.27 microcoulombs and the positive one has a charge of 58.27 microcoulombs.
On a slope where does a marble have to most kinetic energy?
a) it is always the same
b) at the initial position
c) at the final position
d) somewhere between the initial and the final position
Answer:
C
Explanation:
Kinetic energy is the energy of motion. It has the most potential energy at the top but the most kinetic at the bottom after it's accelerated fully down the slope.
Calculate the moment on the following seesaws
5Kg
4m
A student places an object with a mass of m on a disk at a position r from the center of the disk. The student starts rotating the disk. When the disk reaches a speed of 0.8 m/s, the object starts to slide off the disk. What is the coefficient of static friction between the object and the disk?
mass=100 g, r= 0.75 m
Answer:
The coefficient of static friction between the object and the disk is 0.087.
Explanation:
According to the statement, the object on the disk experiments a centrifugal force due to static friction. From 2nd Newton's Law, we can represent the object by the following formula:
[tex]\Sigma F_{r} = \mu_{s}\cdot N = m\cdot \frac{v^{2}}{R}[/tex] (1)
[tex]\Sigma F_{y} = N - m\cdot g = 0[/tex] (2)
Where:
[tex]N[/tex] - Normal force from the ground on the object, measured in newtons.
[tex]m[/tex] - Mass of the object, measured in newtons.
[tex]g[/tex] - Gravitational acceleration, measured in meters per square second.
[tex]v[/tex] - Linear speed of rotation of the disk, measured in meters per second.
[tex]R[/tex] - Distance of the object from the center of the disk, measured in meters.
By applying (2) on (1), we obtain the following formula:
[tex]\mu_{s}\cdot m\cdot g = m\cdot \frac{v^{2}}{R}[/tex]
[tex]\mu_{s} = \frac{v^{2}}{g\cdot R}[/tex]
If we know that [tex]v = 0.8\,\frac{m}{s}[/tex], [tex]g = 9.807\,\frac{m}{s^{2}}[/tex] and [tex]R = 0.75\,m[/tex], then the coefficient of static friction between the object and the disk is:
[tex]\mu_{s} = \frac{\left(0.8\,\frac{m}{s} \right)^{2}}{\left(9.807\,\frac{m}{s^{2}} \right)\cdot (0.75\,m)}[/tex]
[tex]\mu_{s} = 0.087[/tex]
The coefficient of static friction between the object and the disk is 0.087.