Physics 201 MWF10:20 Fall 1993 (Ford)
Exam II Chapts. 6-8 in SZY College Physics
Show all your work. Partial credit will be given if earned. Write your
answers in the blanks provided.
(18 pts) 1. A small block with mass 0.080 kg is attached to a string
of length 3.0 m. The other end of the string is tied to a nail hammered part
way into a horizontal frictionless surface. The block is made to travel in
a horizontal circle of radius 3.0 m. While the block is moving the tension
in the string is 6 N. How much time does it take the block to complete one
revolution?
Ans. ___________________
(20 pts) 2. A small block with mass 0.2 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. At point B at the lowest point of the
track, 5.0 m below A,
the block is observed to have a velocity of magnitude 6.0 m/s.
a) How much work was done by friction during the motion of the block
from point A to point B?
Ans. _______________
b) What is the magnitude of the normal force that the track exerts of
the block when the block is moving through point B?
Ans. ______________
(22 pts) 3. A block with mass 2 kg is placed on a vertical, compressed
spring. The spring has potential energy 80 J stored in it. The spring
is released and the block travels upward. (The block is not
attached to the spring.)
a) What is the speed v of the block when it is 3.0 m above its
initial position? (The block has left the spring at this point.)
Ans. __________________
b) How high does the block rise above its initial position?
Ans. __________________
(20 pts) 4. Block A has a mass of 2 kg and block B has a mass
of 6 kg. The
two blocks are forced together, compressing a spring between them, and the
system is then released from rest on a level, frictionless surface. The
spring is not fastened to either block and drops to the surface after it has
expanded. Block A is moves off to the left with a speed of
6.0 m/s.
a) What is the final speed of block B?
Ans. ____________________
b) How much potential energy was originally stored in the spring?
Ans. ___________________
(20 pts) 5. Two cars arrive at an intersection and collide. The cars
become stuck together as a result of the collision. Immediately after the
collision, the combined object (mass 2000 kg) has a velocity with
magnitude 12 m/s at an angle of 37° , as shown in the sketch.
Car A has mass 800 kg and car B has mass 1200 kg. What was
the speed of each car just before the collision?
Ans. car A (800 kg) ______________________
car B (1200 kg) _________________________