Physics 201 MWF10:20 Fall 1996 (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.


(9 pts) 1. A container with rigid walls contains 5.0 moles of an ideal gas. The gas has C_p = 20.8 J/mol·K. The initial pressure of the gas is 2.0×10⁵ Pa and the initial temperature is 300 K. Then 3000 J of heat energy is removed from the gas while the volume is kept constant. Note: R = 8.314 J/mol·K.

a) What is the change in internal energy of the gas?

Ans. ___-3000 J___

b) What is the final temperature of the gas?

Ans. ___252 K______________

c) What is the final pressure of the gas?

Ans. ___1.68×10⁵ Pa___


(8 pts) 2. An airplane is traveling eastward. A warning siren attached to the plane is emitting sound waves with a frequency of 170 Hz. The speed of sound is 340 m/s. At a point directly behind the plane the wavelength of the sound waves is 3.6 m. What is the speed of the plane?

Ans. ___272 m/s___


(8 pts) 3. The equation of a certain transverse wave is
y = (3.60 cm)  sin([6 rad/s]t + [7 cm^-1]x)

a) In what direction is the wave traveling, +x or -x?

Ans. ___-x___

b) What is the speed of propagation of the wave?

Ans. ___0.858 cm/s___

c) What is the period of the wave motion?

Ans. ___1.05 s___


(14 pts) 4. A block with mass 5.0 kg rests on an incline with slope angle 37°. A horizontal force P = 60 N is applied to the block. Starting from rest the block moves 7.0 m up the incline in 3.0 s.

a) What is the magnitude of the acceleration of the block?

Ans. ___1.56 m/s²___

b) What is the magnitude of the normal force exerted by the incline on the block?

Ans. ___75.2 N___

c) What is the coefficient of kinetic friction between the block and the incline?

Ans. ___0.144___


(13 pts) 5. A rock is thrown from the edge of the roof of a building with a velocity of magnitude v₀ = 12 m/s at an angle of 37° above the horizontal. It is observed that the rock strikes the ground 3.0 s after being thrown.

a) What is the height of the building?

Ans. ___22.5 m___

b) What is the horizontal distance from the base of the building to the point where the rock strikes the ground?

Ans. ___28.8 m___

c) What is the maximum height above the roof reached by the rock during its motion?

Ans. ___2.64 m___

d) What is the magnitude of the velocity of the rock when it is at its maximum height above the roof?

Ans. ___9.6 m/s___


(12 pts) 6. A uniform bar that weighs 40 N is attached by a frictionless hinge to a wall. A horizontal rope holds the bar at an angle of 53° above the horizontal.

a) What is the tension in the rope?

Ans. ___15 N___

b) What is the magnitude of the force that the hinge exerts on the bar?

Ans. ___42.7 N___


(14 pts) 7. A block of mass 2 kg is placed against a compressed spring at the bottom of a 37° incline (point A). The spring initially has 230 J of potential energy stored in it. The spring is released from rest and the block travels up the incline. At point B the block has moved 6.0 m from point A and is no longer in contact with the spring. The incline exerts a constant friction force of magnitude 7.5 N on the block.

a) When the block moves from point A to point B, what is the change in the gravitational potential energy of the block? (You must say whether this change is positive or negative.)

Ans. ___+70.6 J___

b) When the block moves from point A to point B, what is the work done on the block by friction? (You must say whether this work is positive or negative.)

Ans. ___-45 J___

c) What is the speed of the block at point B?

Ans. ___10.7 m/s___


(11 pts) 8. One end of a 5.00 m long rope is attached to the ceiling and a small steel ball of mass 0.4 kg is suspended from the other end. The ball is released from rest at point A.

a) At point B, where the rope is vertical, what is the speed v of the ball?

Ans. ___8.03 m/s___

b) As the ball swings through point B, what is the tension in the rope?

Ans. ___9.08 N___

c) At point C the rope makes an angle of 53° with respect to the vertical. What is the speed of the ball at point C?

Ans. ___5.05 m/s___

d) As the ball swings through point C, what is the tension in the rope?

Ans. ___4.39 N___


(11 pts) 9. A small block on a frictionless tabletop has a mass of 0.050 kg and is attached to a string that passes through a hole in the surface. A person under the table holds the end of the string. The block is originally revolving at a distance of 0.30 m from the hole with a speed of 4.0 m/s. The string is then slowly pulled by the person, shortening the radius of the circle in which the block is revolving to 0.10 m.

a) What then is the speed of the block?

Ans. ___12 m/s___

b) How much work was done by the person who pulled the string?

Ans. ___3.2 J___