Physics 201 MWF10:20 Fall 1998 (Ford)

Exam II Chapts. 5-7 in Cutnell and Johnson, 4th ed.


(12 pts) 1. A satellite is in a circular orbit around an unknown planet. The satellite has a speed of 3.0 × 10⁴ m/s, and the radius of its orbit is 5.0 × 10⁶ m. A second satellite also has a circular orbit around this same planet. The speed of this second satellite is 7.0 × 10⁴ m/s. What is the radius of the orbit of the second satellite?

Ans. _____________


(22 pts) 2. A marble with mass m = 0.015 kg is glued to the end of a 3.0 m long string. The marble is set into motion so that it rotates with constant speed in a horizontal circle. The string makes an angle of 37° with the vertical.

a) What is the tension T in the string?

Ans. _____________

b) What is the magnitude of the acceleration of the marble?

Ans. ____________

c) How much time does it take the marble to complete 1 revolution?

Ans. _____________


(24 pts) 3. A small lump of putty with mass 0.5 kg starts from rest and slides down a quarter-circle section of track, from point A to point B as shown in the sketch. The radius of this section of track is r = 6.0 m.

a) During the motion of the lump of putty from point A to B, friction does -8.0 J of work on it. What is the speed of the lump of putty when it gets to point B at the bottom of the quarter-circle section of track?

Ans._____________

b) At point B the lump of putty strikes a block with mass 2.0 kg and sticks to it. The block is initially at rest on a horizontal surface. What is the speed of the combined object just after the collision, when the putty and block have reached a common velocity? (Neglect the effects of friction between the horizontal surface and the objects during the collision.)

Ans. ____________

c) The coefficient of kinetic friction between the combined object (block plus putty) and the horizontal surface is µ_k = 0.4. What distance does the combined object slide before coming to rest?

Ans. _____________


(22 pts) 4. A small block with mass m = 0.03 kg slides without friction along the curved track shown in the sketch. The circular part of the track has radius R = 2.0 m.

a) The block is released from rest at point A, which is a height h = 9.0 m above the ground. What is the upward normal force exerted by the track on the block as it slides through point B, which is at the bottom of the circular section of the track?

Ans. ______________

b) What minimum height h above the ground must point A have in order for the block not to lose contact with the track at point C, which is at the top of the circular section of track.

Ans. _______________


(20 pts) 5. Blocks A and B are sliding on a horizontal frictionless surface as shown in the sketch. Block A has mass m_A = 6 kg and block B has mass m_B = 4 kg. Initially block A is traveling east and block B is traveling north. After the collision block A is traveling with speed v_A2 = 8 m/s in the direction 37° north of east and block B is traveling east with speed v_B2 = 2 m/s. What are the speeds v_0A and v_0B of the two blocks before the collision?

Ans. v_0A _____________

   v_0B _____________