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Unit 5, Quiz #2

Use the diagram at the right to answer questions #1 and #2.

1. As the pendulum bob swings from position A to position B, its total mechanical energy (neglecting friction and air resistance)

a. decreases.

b. increases.

c. remains the same.


Useful Web Links

Mechanical Energy (15 seconds)

Analysis of Situations in Which Mechanical Energy is Conserved (13 seconds)

 

2. As the pendulum bob swings from position A to position B, its

a. speed decreases

b. potential energy decreases

c. mass decreases

d. kinetic energy decreases

e. kinetic energy remains constant


Useful Web Links

Potential Energy (12 seconds)

Kinetic Energy (4 seconds)

Analysis of Situations in Which Mechanical Energy is Conserved (13 seconds)

Use the following diagram to answer questions #3 - #5. Neglect the effect of friction and air resistance.

3. As the object moves from point A to point D across the frictionless surface, the sum of its potential and kinetic energies

a. decreases, only.

b. decreases and then increases.

c. increases and then decreases.

d. remains the same.

4. The object will have a minimum gravitational potential energy at point

a. A.

b. B.

c. C.

d. D.

e. E.

5. The object's kinetic energy at point C is less than its kinetic energy at point

a. A only.

b. A, B, and C.

c. B and C.

d. C only.

e. E only.


Useful Web Links

Mechanical Energy (15 seconds)

Potential Energy (12 seconds)

Kinetic Energy (4 seconds)

Analysis of Situations in Which Mechanical Energy is Conserved (13 seconds)

 

6. As a rock falls from a cliff in the absence of air resistance, its total mechanical energy is equal to

  1. its potential energy minus its kinetic energy.
  2. its kinetic energy minus its potential energy.
  3. the product of its kinetic and potential energies.
  4. the sum of its potential and kinetic energies.


Useful Web Links

Mechanical Energy (15 seconds)

Analysis of Situations in Which Mechanical Energy is Conserved (13 seconds)

 

7. For each set of units below, identify whether they are units of force, energy, or power.

________

________

________

 

8. Construct a work-energy bar chart for the following physical description.

A skier starts from rest on top of hill A and skis into the valley and back up onto hill B. See diagram at the right. The skier utilizes her poles, applying a force to propel herself across the snow. The initial state is on top of hill A and the final state is on top of hill B. Ignore frictional forces.


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Bar Chart Illustrations (21 seconds)

 

A 60-kg person on a swing starts from rest at a height of 3.2-m above the ground (position A). At position B, the student is 1.0 m above the ground. At position C (1.9 m above the ground), the person projects from the seat and travels as a projectile along the path shown. At point F, the student is a mere picometer above the ground. Assume negligible air resistance throughout the motion. Use this scenario to answer questions #9-13.

9. Carefully construct energy-bar charts for this motion for the five indicated positions (omit E).


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Bar Chart Illustrations (21 seconds)

 

10. Determine the total mechanical energy of the swinger. PSYW


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Mechanical Energy (15 seconds)

 

11. Determine the swinger's speed at position B. PSYW


Useful Web Links

Analysis of Situations in Which Mechanical Energy is Conserved (13 seconds)

 

12. Determine the swinger's speed at position F. PSYW


Useful Web Links

Analysis of Situations in Which Mechanical Energy is Conserved (13 seconds)

 

13. If an 80-kg swinger did the same motion, would the final speed (at position F) be greater than, less than, or equal to the final speed of the 60-kg swinger? Explain clearly and logically.


Useful Web Links

Analysis of Situations in Which Mechanical Energy is Conserved (13 seconds)

 

 

14. An 800-kg car moving at 25.0 m/s runs out of gas just prior to ascending (climbing) a hill. Supposing that -40000 J of work are done upon the car by air resistance (and other external forces), determine the height to which the car will coast up the hill before stopping. PSAYW


Useful Web Links

Analysis of Situations Involving External Forces (21 seconds)

 

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© Tom Henderson, 1996-1998


Glenbrook South High School.

Last updated on 12/10/98.