Physics 201 MWF10:20 Fall 1994 (Ford)
Final Exam Chapts. 1--23 in SZY College Physics
Show all your work. Partial credit will be given if earned. Write your
answers in the blanks provided.
(12 pts) 1. A 0.2 kg block is placed against a compressed spring. The spring
is released and the block travels along a horizontal surface. If the spring
had 4.0 J of potential energy stored in it and the coefficient of kinetic
friction between the block and the surface is µk = 0.40,
how far
does the block travel before coming to rest? (The block is not
attached to the spring.)
Ans. ________________
(12 pts) 2. Two cars arrive at an intersection and collide. Car A has
mass 800 kg and car B has mass 1200 kg. Just before the collision
car A
is moving north with a speed of 25.0 m/s and car B
is moving east with a speed of 12.0 m/s.
The cars become stuck together as a result of the collision.
Immediately after the collision, what is the speed of the combined object
(mass 2000 kg)?
Ans. ________________
(4 pts) 3. A duck floating in a lake bobs up and down because of the
waves on the
surface of the water. The distance between wave crests on the lake is 4.0 m
and it takes the duck 1.2 s to travel from its highest point to its
lowest. How fast are the waves traveling?
Ans. _______________
(6 pts) 4. A string that is 2.4 m long is tied to rigid supports at
both ends. The speed of transverse waves on the string is 300 m/s.
a) If the string is vibrating in its 2nd overtone standing wave, what is
the distance between adjacent nodes of the standing wave?
Ans. ______________
b) What is the frequency of the 2nd overtone standing wave?
Ans. ______________
(15 pts) 5. When the system in the sketch is released from rest, the 10 kg
block accelerates down the incline with a = 4.0 m/s2. The
coefficient of kinetic friction between the 10 kg block and the incline
is µk = 0.2. The pulley is massless and frictionless.
a) What is the magnitude of the friction force exerted on the 10 kg block
while it is moving?
Ans. ______________
b) What is the tension T in the rope connecting the blocks (while the
blocks are moving)
Ans. _______________
c) What is the mass m of the hanging block?
Ans. ______________
(15 pts) 6. A football kicked from ground level at a speed of
40 m/s and at an angle of 53° above the horizontal
strikes the wall of a tall building 4.0 s after being kicked.
a) What is the horizontal distance from the point where the football was kicked
to the base of the building?
Ans. ___________________
b) What is the maximum height above ground reached by the ball during its
motion?
Ans. ________________
c) What is the magnitude of the velocity of the ball just before it strikes
the building?
Ans. _________________
(12 pts) 7. A uniform bar 8 m long and weighing 120 N is attached at
one end to a wall by a frictionless hinge. The bar is held horizontal by a
cable as shown in the sketch.
a) What is the tension in the cable?
Ans. __________________
b) What are the horizontal and vertical components of the force the hinge
exerts on the bar?
Ans. horizontal ____________
vertical _______________
(12 pts) 8. An object with density 400 kg/m3 is suspended from a
string. When the object is in air, the tension in the string is 8.0 N. The
object is then completely immersed in a liquid with density
300 kg/m3. Calculate
a) the volume of the object.
Ans. ______________
b) the buoyant force exerted by the liquid on the object.
Ans. ______________
c) the tension T in the string when the object is immersed in the liquid.
Ans. ______________
(12 pts) 9. A cylinder with a moveable piston contains 2.0 moles of an ideal gas
at an initial temperature of 250 K and with an initial volume of
0.03 m3.
For this gas Cp = 20.8 J/mol·K and
CV = 12.5 J/mol·K. The gas constant is
R = 8.314 J/mol·K. If 4000 J of heat energy is
added to the gas while the pressure of the gas is kept constant,
a) what is the final temperature of the gas?
Ans. ______________
b) what is the final volume of the gas?
Ans. _____________
c) what is the amount of work done by the gas during this process?
Ans. _____________