A sphere of mass m and a of mass 5m are attached to the ceiling by massless stri

Question

A sphere of mass m and a of mass 5m are attached to the ceiling by massless strings of identical length forming twin pendulums of length L. The 1m sphere is drawn to the left so that its center of mass has been raised a distance h and its then released. As the 1m sphere moves back through equilibrium it hits and adheres to the 5m sphere. The combined system swings to the right, eventually reaching some maximum height before returning to equilibrium. 

1. How much work did gravity do on the 1m sphere when it was moved from equilibrium to its release point.

a. mgh

b.-mgh

c.1/2mgh

d. cannot be determined.

2. In this problem:

a. momentum and energy are always conserved

b. energy alone is conserved

c. momentum alone is conserved

d.momentum is conserved only during the collision and mechanical energy is conserved at all times except during the collision.

3. The maximum height reached by the combined spheres would be most increased by:

a. doubling the initial height (h)

b.halving the mass of the 5m ball (to 2.5m)

c. doubling the mass of the 1m ball (to 2m)

d. either B or C

4. If the collision was elastic rather than inelastic how would the post-elastic-collision speeds compare to the post-inelastic-collision speed?

a. The 1m sphere would be moving faster, the blue slower.

b. The 1m sphere would be moving slower, the blue faster.

c. Both 1m and 5m balls would be moving faster than the post-inelastic-collision speed.

d.Neither 1m and 5m balls would be moving faster than the post-inelastic-collision speed. 

5. What was the speed of the 1m sphere just before its collision?

a. (2gh)1/2

b. (gh)1/2

c. g(L2-h2)1/2

d. 1/2gh2

Explanation / Answer

1. How much work did gravity do on the 1m sphere when it was moved from equilibrium to its release point.

a. mgh

b.-mgh

c.1/2mgh

d. cannot be determined.



2. In this problem:

a. momentum and energy are always conserved

b. energy alone is conserved

c. momentum alone is conserved

d.momentum is conserved only during the collision and mechanical energy is conserved at all times except during the collision.



3. The maximum height reached by the combined spheres would be most increased by:

a. doubling the initial height (h)

b.halving the mass of the 5m ball (to 2.5m)

c. doubling the mass of the 1m ball (to 2m)

d. either B or C



4. If the collision was elastic rather than inelastic how would the post-elastic-collision speeds compare to the post-inelastic-collision speed?

a. The 1m sphere would be moving faster, the blue slower.

b. The 1m sphere would be moving slower, the blue faster.

c. Both 1m and 5m balls would be moving faster than the post-inelastic-collision speed.

d.Neither 1m and 5m balls would be moving faster than the post-inelastic-collision speed.



5. What was the speed of the 1m sphere just before its collision?

a. (2gh)1/2

b. (gh)1/2

c. g(L2-h2)1/2

d. 1/2gh2

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.