Work and Energy Worksheet
Section 1 Work:
1. A person pulls a toboggan for a distance of 35.0m along the snow. The force in the rope (tension) is 94.0N. How much work is done on the sled?
Solution:
W= Fd W= 94.0N x 35.0m
W= 3290 Nm or J
2. The cable of a large crane applies a force of 2.2x10^4N to a demolition ball as it lifts it vertically a distance of 7.6m. a) How much work is done on the ball? b) Is the work positive or negative? Why?

Solution:
A.) W=( 2.2x10^4N) ( 7.6 m) W= 1.6x10^5 Nm or J
B.) Positive, because the force on the system is positive.
3. When spring arrives a woman packs her winter clothes in a box and lifts it at a constant velocity to the top shelf of her closet, a distance of 1.8m above the floor. If the clothes weigh 150N, how much work is done in lifting them?

Solution:
W= (150N) (1.8M) W= 270Nm or J
4. A luggage carrier is pulled 50.0m with a force of 30.0N, how much work is done on the carrier?
Solution:
W= (30.0N) (50.0m) W= 1500Nm or J
5. You are moving into a new apartment. Your weight is 685N and your belongings have a weight of 915N. How much work does the elevator do in lifting you and your belongings 5 stories (15.2m)?
Solution:
W= (685N+915N) (15.2m) W= (1600N) (15.2m) W= 24,320Nm or J Section 2 Gravitational Potential Energy:
6. A 0.15kg ball is thrown 9.0m straight up. What is the work done by the gravitational force? And what is the change in PE? (Notice anything?)
Solution:
PE= m*a*h PE= (0.15kg) (9.8 m/s^2) (9.0) PE= 13.23 kg m^2/s^2 or J - The change in PE and the calculated on the 1st question are the same. 7. A shot-putter puts a shot (weight 71.1N) that leaves his hand at a distance of 1.52m above the ground. a) Find the work done by gravity when the shot reaches a height of 2.13m. b) Determine the change in potential energy.

Solution:
a.) W=( 71.1N) (2.13m) W= 151.44Nm or J
b.) PE= (71.1N)...

...PotentialEnergy
• Definition and Mathematics of Work
• Calculating the Amount of Work Done by Forces
• PotentialEnergy
• Kinetic Energy
• Mechanical Energy
• Power
An object can store energy as the result of its position. For example, the heavy ball of a demolition machine is storing energy when it is held at an elevated position. This stored energy of position is referred to as potentialenergy. Similarly, a drawn bow is able to store energy as the result of its position. When assuming its usual position (i.e., when not drawn), there is no energy stored in the bow. Yet when its position is altered from its usual equilibrium position, the bow is able to store energy by virtue of its position. This stored energy of position is referred to as potentialenergy. Potentialenergy is the stored energy of position possessed by an object.
Gravitational PotentialEnergy
The two examples above illustrate the two forms of potentialenergy to be discussed in this course - gravitational potentialenergy and elastic potentialenergy. Gravitational potential...

...the transfer of energy; work is done on an object when an applied force moves it through a distance. The link between work and energy is work done equals energy transferred. The units for the two are also the same (joules). E.g. 500J of work = 500J of kinetic energy.
Work is calculated with the formula: work done=force x distance moved
For example, if a force of 10 newton (F = 10 N) acts along point that travels 2 meters (d = 2 m), then it does the work W = (10 N)(2 m) = 20 N m = 20 J. This is approximately the work done lifting a 1 kg weight from ground to over a person's head against the force of gravity. Notice that the work is doubled either by lifting twice the weight the same distance or by lifting the same weight twice the distance.
Examples:
Force is measured in newton’s (N)
Distance is measured in meters (M)
Work done is measured in joules (J)
Examples of work done:
How much work is done by a person who uses a force of 27.5N to move a grocery buggy 12.3m?
W = F x d = (27.5N) (12.3m) = ?
Equation
W = 338.25J
Answer
55, 000J of work is done to move a rock 25m. How much force was applied?
F = W = 55,000J = ?
d 25m
Equation
F = 2200J
Answer
You and 3 friends apply a combined force of 489.5N to push a piano. The amount of work done is 1762.2J. What distance did the piano move?
Equation
d= W = 1762.2J =
F 489.5N
Answer
d = 3.6m...

...system. |
| | It would take less time to reach its bound orbit. |
| | It would orbit the earth at a faster velocity. |
| | | | |
Question 7 | 1.61 points | Save |
| When energy is converted from one form to another, a tiny amount is inevitably lost. | | | | |
| | True |
| False |
| | | | |
Question 8 | 1.61 points | Save |
| There is no gravity in space. | | | | |
| | True |
| False |
| | | | |
Question 9 | 1.61 points | Save |
| The Moon is slowly moving away from the earth. | | | | |
| | True |
| False |
| | | | |
Question 10 | 1.61 points | Save |
| Which of the following statements correctly describes the law of conservation of energy? | | | | |
| | | The total quantity of energy in the universe never changes. |
| | An object always has the same amount of energy. |
| | It is not really possible for an object to gain or lose potentialenergy, because energy cannot be destroyed. |
| | Energy can change between many different forms, such as potential, kinetic, and thermal, but it is ultimately destroyed. |
| | The fact that you can fuse hydrogen into helium to produce energy means that helium can be turned into hydrogen to produce energy. |
| | | | |...

...PotentialEnergyPotentialEnergy is a type of energy that does not involve motion. It is the energy that is stored up. The more work done to change an object's position or shape, the more potentialenergy it has. For example, a person on a ladder has more potentialenergy than a person on the ground because they have done more work to get up there.
Kinetic Energy
Kinetic Energy is the energy of motion. The more work an object has done, the more kinetic energy it has. the amount of kinetic energy an object has can be calculated by the formula:
KE = 1/2 MV2
It can be defined as the works needed to accelerate an object of a certain mass from rest to its stated velocity.
Thermal Energy
Thermal Energy is the energy an object has related to temperature. It comes from all of the energy of the particles in an object. Typically, objects with a higher temperature release more thermal energy than objects with a lower temperature because their atoms and molecules move faster. Within every energy conversion, there is thermal energy emitted.Chemical Energy
Chemical Energy is the potential of a chemical substance to undergo a...

...WORK and ENERGY
Work done by a constant force
1- The drawing shows a plane diving toward the ground and then climbing back upward. During each of these motions, the lift force acts perpendicular to the displacement , which has the same magnitude, 1.7 × 103 m, in each case. The engines of the plane exert a thrust , which points in the direction of the displacement and has the same magnitude during the dive and the climb. The weight of the plane has a magnitude of 5.9 × 104 N. In both motions, net work is performed due to the combined action of the forces , and .
a. Is more net work done during the dive or the climb? Explain.
b. Find the difference between the net work done during the dive and the climb.
Answer:
a. More net work is done during the dive.
b. 6.8 × 107 J
2- Find the work done by a force through a displacement of 3m in the positive x direction
Work-Energy theorem and kinetic energy
3- The mass of the space probe is 474-kg and its initial velocity is 275 m/s. If the 56.0-mN force acts on the probe through a displacement of 2.42×109m, what is its final speed?
Answer:
4- Example 2: Skier
Gravitational PotentialEnergy, Conservative versus Nonconservative Forces
5- The gymnast leaves the trampoline at an initial height of 1.20 m and reaches a maximum height of 4.80 m before falling back down. What was the initial speed of the...

...POTENTIALENERGY DIAGRAM
In physics the terms of mechanical energy usually refers to Potentialenergy (U) and Kinetic Energy (K). In the absence of non-conservative, or dissipative forces, these energies obey the law of conservation of energy, or ΔU + ΔK = 0.
That is, when a system is only acting under the influence of conservative forces its total energy content never changes, the energy just converts between forms.
At any point in the cycle, the total energy is constant, U + K = Umax = Kmax. Remember our two relationships involving work
The work done by a conservative force decreases an object's potentialenergy while it is increasing its kinetic energy
Defining the initial potentialenergy Uo = 0, gives us
Using the calculus, we see that our desired expression of the instantaneous restoring force being equal to the negative derivative of the potentialenergy function.
See also this PotentialEnergy diagram.
The curve represents the value of potentialenergy U as a function of the particle's coordinate x. The horizontal line above the curve represents the constant value of the total energy of the particle E. The total...

...Potential and Kinetic Energy lab report
Caty Cleary
4th period
Problem statement:
How does the drop height (gravitational potentialenergy) of a ball affect the bounce height (kinetic energy) of the ball?
Variables:
Independent variable- drop height
Dependent variable- bounce height
Controlled variables (constants) - type of ball, measurement(unit), place bounced, and the materials used for each experiment.
Hypothesis:
If the gravitational potentialenergy (drop height) of the ball is increased, then the kinetic energy (bounce height) will increase because the ball will pick up speed on its way down which will cause it to apply more force to the ground, making the ball bounce higher.
Materials and Procedure:
Ball(s), meter stick, balance and a flat surface.
Procedure-
1. Tape the meter stick to the side of the table with the 0-cm end at the bottom and the 100-cm end at the top. Be sure that the meter stick is resting flat on the floor and is standing straight up.
2. Choose a ball type and record the ball type in the data table.
3. Use the triple beam balance to determine the mass of the ball and record the ball’s mass in the data table.
4. Calculate the gravitational potentialenergy (GPE) for the ball at each drop height. Record GPE in the data table.
5. For Trial 1, hold the ball at a height of 40 cm, drop the...

...
PotentialEnergy:
Potentialenergy is the stored energy of position possessed by an object.
PotentialEnergy Formula :
PotentialEnergy: PE = m x g x h
Mass:
Acceleration of Gravity:
Height:
where,
PE = PotentialEnergy,
m = Mass of object,
g = Acceleration of Gravity,
h = Height of object,
Examples:
1. A cat had climbed at the top of the tree. The Tree is 20 meters high and the cat weighs 6kg. How much potentialenergy does the cat have?
m = 6 kg, h = 20 m, g = 9.8 m/s2(Gravitational Acceleration of the earth)
Step 1: Substitute the values in the below potentialenergy formula:
PotentialEnergy: PE = m x g x h
= 6 x 9.8 x 20
PotentialEnergy: PE = 1176 Joules
2. On a 3m ledge, a rock is laying at the potentialenergy of 120 J. What will be the mass of the rock.
PE = 120 J, h = 3m, g = 9.8 m/s2(Gravitational Acceleration of the earth)
Step 1: Substitute the values in the below Velocity formula:
3. A ball of mass 2 Kg is kept on the hill of height 3Km. Calculate the potentialenergy possessed by it?
Solution:
Mass of the...

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