Physics 201 MWF10:20 Fall 1997 (Ford)
Exam II Chapters 6--8 in SZY College Physics

Show all your work. Partial credit will be given if earned. Write your answers in the blanks provided.


(20 pts) 1. A small block with mass 0.40 kg is released from rest at point A that is at the top of a curved track that has the shape of a semicircle of radius 5.0 m. During the motion of the block from point A to point B, the work done by the friction force on the block is -12 J.

a) What is the speed of the block when it reaches point B?

Ans. ___6.16 m/s___

b) What is the magnitude of the normal force that the track exerts on the block when the block is moving through point B?

Ans. ___6.96 N___


(20 pts) 2. A block of mass m is attached to a vertical rod by means of two strings. When the system rotates about the axis of the rod, the strings are extended as shown in the diagram. The tension in the upper string is 80.0 N and the tension in the lower string is 60.0 N.

a) What is the mass m of the block?

Ans. ___1.63 kg___

b) How much time does it take for the system to make one revolution?

Ans. ___0.39 s___


(22 pts) 3. A light spring with force constant k = 200 N/m is attached to the ceiling. A mass of 2.0 kg is attached to the lower end of the unstretched spring and then is released from rest.

a) What is the speed of the mass when it has traveled downward 0.060 m from the point where it was released?

Ans. ___0.906 m/s___

b) What maximum distance does the block stretch the spring?

Ans. ___0.196 m___


(22 pts) 4. A bullet with a mass of 0.006 kg and traveling in a horizontal direction with a speed v₀ strikes a wooden block of mass 0.50 kg that is initially at rest on a horizontal surface. The bullet passes through the block and emerges with a speed of 100 m/s. After the collision with the bullet the block slides a distance of 0.30 m along the surface from its initial position before coming to rest. The coefficient of kinetic friction between the block and the surface is 0.20.

a) What was the speed of the block immediately after the bullet has passed through it?

Ans. ___1.08 m/s___

b) What was the initial speed of the bullet?

Ans. ___190 m/s___


(16 pts) 5. A stone with mass of 0.100 kg rests on a frictionless horizontal surface. A bullet of mass 0.0025 kg, traveling horizontally at 500 m/s, strikes the stone and rebounds horizontally at right angles to its original direction with a speed of 300 m/s. What is the magnitude and direction (the angle ) of the velocity of the stone after it is struck?

Ans. magnitude ___14.6 m/s___

direction ___31.0°___