Physics 201 MWF10:20 Fall 1996 (Ford)
Exam I 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 of mass 0.050 kg slides along a track as shown in the
sketch. Point B is 0.60 m above point A. At point A the
block has
speed v = 9 m/s. At point B its speed is
v = 4 m/s. How much work is done by the friction force on the
block as the block moves from point A to point B?
Ans. ___________________
(18 pts) 2. A small car with mass m = 0.3 kg is traveling in a
vertical circle inside a hollow cylinder of radius R = 1.2 m.
a) When the car is at point A, at the bottom of the circular path,
its speed is v = 9.0 m/s. What is the normal force that the cylinder
exerts on the car at this point?
Ans. ____________________
b) When the car is at point B, at the end of a horizontal diameter of the
cylinder, its speed is v =6.0 m/s. What is the normal force
that the cylinder exerts on the car at this point?
Ans. ___________________
c) What is the minimum speed that the car must have at point C, at the
top of the circular path, if it is NOT to lose contact with the cylinder there?
Ans. __________________
d) When the car at point C has the minimum speed calculated in part (c),
what is the magnitude and direction of its acceleration?
Ans. magnitude ___________________
direction _________________
(22 pts) 3. A block of mass 2.0 kg on a horizontal surface is placed against
a long spring that is compressed 0.4 m. The spring has force constant
250 N/m. The coefficient of kinetic friction between the block
and the surface is µk = 0.30. The spring is released and the
block moves to the right.
a) When the block has moved 0.25 m from its initial position the spring is still
compressed 0.15 m. At this point what is the speed of the block?
Ans. ______________________
b) How far from its initial position, where the spring is compressed 0.4 m,
does the block travel before it comes to rest. (Note: The block is not
attached to the spring so after it travels 0.4 m it leaves the spring behind.)
Ans. ____________________
(20 pts) 4. Blocks A and B are sliding on a horizontal
frictionless surface as shown in the sketch. Block A has mass
mA = 6 kg and
block B has mass mB = 4 kg. Initially block A
is traveling east and block B is traveling north. After the
collision block A is traveling
with speed vA2 = 5 m/s in the direction 37° north
of east and block B is traveling east with speed
vB2 = 2 m/s. What are the speeds vA1
and vB1
of the two blocks before the collision?
Ans. vA1 _________________
vB1 _____________________
(22 pts) 5. A wooden block with mass 3.2 kg is at rest on a horizontal surface.
The coefficient of kinetic friction between the block and the surface is
µk = 0.25. A bullet of mass 0.05 kg traveling at
150 m/s strikes the block and becomes embedded in it.
As a result of the collision, the block moves to the right along the surface.
How far does the block travel before coming to rest?
Ans. __________________