Only friction between the air and the satellite piece prevents the formula from the conservation of energy from being completely accurate. This is stated as _____.

Question

KE = 1/2mv2

PEg = mgh

PEelastic = 1/2kx2

KEi + PEi = KEf + PEf
2.
Choose the best answer.

Which equation describes the energy conversions in the motion of roller coaster car dropping down a hill?

3.
​Choose the best answer.

​​​(Double points) A mechanic used a wrench 0.6 meters long to loosen rusted lug nuts on a truck wheel. By standing on the end of the wrench, he was able to apply his entire 100 kg weight to the wrench. How much torque did he apply?

60 N -m

962.5 N-m

588 N-m

980 N-m
4.
Choose the best answer.

A falling satellite piece has a kinetic energy of 47 J, while its potential energy is 198 J. What is the piece's mechanical energy?

198 J

245 J

9.0 J

20.0 J
5.
Choose the best answer.

On September 24, 2011, 26 pieces of a satellite were predicted to fall to the earth's surface. Since the satellite pieces were orbiting the earth from a height of 50 miles, they had _____, or energy due to their position.

mechanical

inertial

potential

kinetic
6.
Choose the the correct units.
A(n) _____ or _____ may be used to express power.

dyne

ampere

joule

horsepower

watt
7.
​Choose the best answer.

​​​(Double points) Check all that apply. How much work did a waitress do if she expended 3.2 N when she pushed a cart a total of 4.6 meters?

8.
Choose the best answer.

A little girl at a daycare pushes a toy wooden duck. She applied force to move the mass a distance: therefore she performed _____.

inertia

matter

work

tension
9.
Choose the best answer.

On September 24, 2011, 26 pieces of a satellite were predicted to fall to the earth's surface. Once the satellite pieces began to fall, their potential energies were converted to _____, or energy that objects possess due to motion.

gravitational

potential

kinetic

inertial
10.
Choose the best answer.

On September 24, 2011, 26 pieces of a satellite were predicted to fall to the earth's surface. Once the satellite pieces began to fall, their potential energies were converted to kinetic energy. These pieces hit the earth with the force of their _____ energy or their potential energy combined with their kinetic energy.

inertial

potential

kinetic

mechanical
11.
Choose the best answer.

The mechanical energy of a moving object can be calculated by the following formula _____.

PEelastic = 1/2kx2

ME=KE+PE

PE = mgh

KE = 1/2mv2
12.
Choose the best answer.

On September 24, 2011, 26 pieces of a satellite were predicted to fall to the earth's surface.The satellite pieces were orbiting the earth from a height of 50 miles and their potential energy can be expressed by the formula:

PE=KE+PE

PEelastic = 1/2kx2

PE = mgh

KE = 1/2mv2
13.
Choose the best answer.

Work is measured in _____.

joules

horsepower

positive work

scalar
14.
​Choose the best answer.

​​​(Double points) On September 24, 2011, 26 pieces of a satellite were predicted to fall to the earth's surface.The satellite pieces were orbiting the earth from a height of 50 miles. If one piece had a mass of 213 kg and another a mass of 59 kg, which one would have the greater potential energy?

213 kg

59 kg

they both have the same.

neither
15.
​Choose the best answer.

​​​(Double points) A waitress expended 3.2 N when she pushed a cart a total of 4.6 meters, if she completed this task in 2 minutes, how much power did she use?

16.
Choose the best answer.

If we measured the rate work is accomplished, we would be measuring _____.

inertia

tension

work

power
17.
Choose the best answer.

The amount of work necessary to move an object can be expressed in _____.

horsepower

joules

watts

amperes
18.
Choose the best answer.

If a satellite piece with a mass of 213 kg lands on the earth's surface, what would its potential energy due to gravity be?

0 J

9.0 J

0.8 J

213 J

Answer 1

Here are the answers to your questions one by one:

1. Only friction between the air and the satellite piece prevents the formula from the conservation of energy from being completely accurate. This is stated as mechanical energy loss.

2. The equation that describes the energy conversions in the motion of a roller coaster car dropping down a hill is KEi + PEi = KEf + PEf.

3. The mechanic applied torque calculated by the formula τ = r * F, where r = 0.6 m and F = weight in Newtons. The weight can be calculated as F = m * g = 100 kg * 9.8 m/s² = 980 N. Therefore, Torque = 0.6 m * 980 N = 588 N-m.

4. The mechanical energy of the falling satellite piece is the sum of its kinetic and potential energy: Mechanical Energy = KE + PE = 47 J + 198 J = 245 J.

5. Since the satellite pieces were orbiting the earth from a height of 50 miles, they had potential energy, or energy due to their position.

6. A(n) watt or horsepower may be used to express power.

7. To find the work done by the waitress, use the formula: Work = Force × Distance. Work = 3.2 N × 4.6 m = 14.72 J.

8. The little girl performed work.

9. The potential energies of the satellite pieces were converted to kinetic energy, or energy that objects possess due to motion.

10. The pieces hit the earth with the force of their mechanical energy or their potential energy combined with their kinetic energy.

11. The mechanical energy of a moving object can be calculated by the following formula: ME = KE + PE.

12. The potential energy can be expressed by the formula: PE = mgh.

13. Work is measured in joules.

14. The piece with a mass of 213 kg would have greater potential energy since potential energy is directly proportional to mass.

15. Power can be calculated using the formula Power = Work / Time. From question #7, Work = 14.72 J. Time = 2 minutes = 120 seconds. Thus, Power = 14.72 J / 120 s = 0.1223 W (or approximately 0.12 W).

16. If we measured the rate work is accomplished, we would be measuring power.

17. The amount of work necessary to move an object can be expressed in joules.

18. The potential energy due to gravity for the satellite piece with a mass of 213 kg, at the height near Earth's surface (assuming g = 9.8 m/s²), would be PE = mgh. However, if it is already on the Earth's surface, PE would be 0 J.

Please let me know if you need any further clarification!