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PH105Exam A - keyApril 30, 2013

  1. A kicker attempts a 30 m field goal. He kicks the ball at an angle of 35o above the ground with an initial speed of 20 m/s. How long does it take for the ball to reach the goal post?

A. 1.83 s

B. 2.34 s

C. 1.17 s

D. 1.5 s

E. 2.6 s

  1. What is the maximum elevation of the ball in the previous problem?

A. 13.4 m

B. 20.4 m

C. 13.7 m

D. 8.6 m

E. 6.7 m

  1. A ball is thrown straight down at 25 m/s from the top edge of a building 50 m high. What is its speed just before it hits the ground? Neglect air resistance.

A. 25 m/s

B. 30 m/s

C. 34 m/s

D. 40 m/s

E. 45 m/s

  1. The position of a particle is given as a function of time as x(t) = 24t – 2t3, where x is in meters and t is in seconds. How far does the car travel in the positive x direction?

A. 22 m

B. 18 m

C. 32 m

D. 12 m

E. 0 m

  1. A Mack truck pushes a motorcycle up a hill with increasing speed. The force that the truck exerts on the motorcycle is

A. greater than the force exerted by the motorcycle on the truck.

B. less than the force exerted by the motorcycle on the truck.

C. the same as the force exerted by the motorcycle on the truck.

D. Need more information to decide which of the above is correct.

  1. A 5 kg block on a flat frictionless table is pulled north with a 15 N force and west with a 20 N force. The magnitude of the acceleration of the block is

A. 7 m/s2

B. 1 m/s2

C. 5 m/s2

D. 25 m/s2

E. 3.5 m/s2

  1. A horizontal force of 5.0 N pushes a 0.50 kg block against a vertical wall. The block is initially at rest. If the coefficient of static friction, µs, is 0.90, and the coefficient of kinetic friction, µk , is 0.80, the frictional force is:

A.5.0 N

B. 4.9 N

C. 4.5 N

D. 4.0 N

E. 0.0 N

  1. A car rounds a circular, flat track with radius of curvature 400 m at 25 m/s. What minimum coefficient of friction will keep the car from skidding?

A. 0.16

B. 0.61

C. 0.39

D. 0.64

E. 0.06

  1. A block of mass m = 100 g slides down a frictionless track, as shown below. The block has an initial height of h1 = 5.0 m and is initially at rest. What will be its speed when it reaches the end of the track where its height is h2 = 2.0 m and its horizontal displacement is d = 6.0 m?

A. 3.7 m/s

B.6.3 m/s

C. 7.7 m/s

D. 9.9 m/s

E. 11 m/s

  1. A man pushes an 8.2 kg crate a distance of 5.0 m upward along a frictionless slope that makes an angle of 30o with the horizontal. The force he exerts is parallel to the slope. If the speed of the crate is constant, then the work done by the man is:

A. -350 J

B. 40 J

C. 70 J

D. 200 J

E. 350 J

  1. In a baseball game, a 145 g ball enters the strike zone with a speed of 35.0 m/s. The batter hits the ball, and it leaves the bat with a speed of 40.0 m/s in exactly the opposite direction. If the bat was in contact with the ball for 1.50 ms, what is the magnitude of the average force exerted by the bat on the ball?

A.7250 N

B. 483 N

C. 10.9 N

D. 7.25 N

E. 483000 N

  1. A 300 g bird flying at 6.0 m/s sees a 10 g insect heading straight toward it with a speed of 30 m/s. The bird opens its mouth and swallows the insect. What is the bird's speed immediately after swallowing the insect? Air resistance can be ignored.

A. 6.8 m/s

B. 5.8 m/s

C. 3.7 m/s

D. 4.8 m/s

E. 6.0 m/s

  1. You want to knock over an upright object by hitting it with a ball. You can choose either a bouncy ball or a sticky ball. The balls have the same mass. Which do you use?
  1. bouncy ball
  2. sticky ball
  3. doesn’t matter
  1. A projectile traveling north explodes into three equal pieces. One piece travels west and one piece travels south. The third piece travels

A. north

B. between north and east

C. between north and west

D. between east and south

E. not enough information

  1. A satellite is in circular orbit around a spherical asteroid, at an altitude of 100 km above the surface, moving at a uniform speed of 80.0 m/s. If the asteroid has a radius of 321 km, what is the mass of the asteroid? (use G = 6.67  10-11 N·m2/kg2)

A. 4.04  1019kg

B. 3.08  1019kg

C. 9.60  1018kg

D. 4.04  1016kg

E. 9.60  1015kg

  1. A disk has a rotational inertia of 20 kg·m2 relative to its axis of rotation, and can rotate without friction. A torque of 10 N·m is applied. It the disk starts from rest, how many revolutions will it perform in 10 s?

A. 16 revs

B. 0.80 revs

C. 8.0 revs

D. 25 revs

E. 4.0 revs

  1. A man of mass 80 kg stands on the edge of a playground carousel that is rotating at an angular speed of 2.0 rad/s. The carousel has a moment of inertia of 1000 kg·m2, and a radius of 3.0 m. If the man walks to the center of the carousel, what will the angular speed then be?

A.2.0 rad/s

B. 3.4 rad/s

C. 1.2 rad/s

D. 2.6 rad/s

E. 0.0 rad/s

  1. Several round objects are released simultaneously from rest at the top of an inclined plane and allowed to roll without slipping. Which is first to reach the bottom?

A. solid disk

B. thin hoop

C. solid ball

D. hollow ball

E. same for all

  1. A mass hanging from the end of a spring oscillates with a period of 1.0 s. If the mass is doubled, then the period of oscillation is:

A.0.50 s

B. 0.71 s

C. 1.0 s

D. 1.4 s

E. 2.0 s

  1. A pendulum has a period of 1.0 s on the surface of earth. What would be its period at the top of a tower 4000 miles high? Assume the radius of earth is 4000 miles.

A. 2.0 s

B. 4.0 s

C. 0.50 s

D. 0.25 s

E. 1.4 s

  1. A transverse wave on a string is given by y = (0.06 m) sin(2x + 10t+ 4), where x is in meters and t is in seconds. The wave is traveling at

A. 10 m/s in the positive x direction

B. 2.5 m/s in the positive x direction

C. 0.06 m/s in the negative x direction

D. 3.1 m/s in the positive x direction

E. 5 m/s in the negative x direction

  1. A 0.85 m long organ pipe is open at one end and closed at the other. What are the three lowest resonance frequencies? Assume the speed of sound to be 340 m/s.

A. 100 Hz, 300 Hz, 500 Hz

B. 100 Hz, 200 Hz, 300 Hz

C. 200 Hz, 600 Hz, 1000 Hz

D. 200 Hz, 400 Hz, 600 Hz

E. 400 Hz, 800 Hz, 1200 Hz

  1. A police car traveling at 40 m/s chases a motorist traveling at 30 m/s. If the frequency of the police car's siren is 500 Hz (as heard by the policeman), what frequency does the motorist hear? Assume the speed of sound to be 340 m/s.

A. 517 Hz

B. 484 Hz

C. 617 Hz

D. 487 Hz

E. 515 Hz

  1. A solid rock, suspended in air by a spring scale, has a measured mass of 9.00 kg. When the rock is completely submerged in water, the scale reads 3.30 kg. If the density of water is 1.00  103 kg/m3, what is the density of the rock?

A. 2.73  103 kg/m3

B. 1.00  103 kg/m3

C. 0.732  103 kg/m3

D. 1.58  103 kg/m3

E. 9.00  103 kg/m3

  1. Water flows in a horizontal pipe with variable cross section. At point A the speed is 2.0 m/s and at point B the speed is 1.0 m/s. What is the difference in pressure between the two points? The density of water of 1000 kg/m3.

A. 1500 Pa

B. 500 Pa

C. 2500 Pa

D. 1000 Pa

E. 9800 Pa

  1. An ideal monatomic gas expands at a constant pressure of 10 kPafrom 0.01 m3 to 0.03 m3. If it absorbs 500 J of heat during this process, what is its change in internal energy?

A. 200 J

B.300 J

C.400 J

D.500 J

E.700 J

  1. The rms speed of O2 molecules at a certain temperature is 400 m/s. What would be the rms speed of He atoms at this same temperature? The molecular mass of O2 is 32 g/mole and the atomic mass of He is 4 g/mole.

A. 3200 m/s

B. 141 m/s

C. 1600 m/s

D. 800 m/s

E. 1130 m/s

  1. 50 g of ice is melted at 0o C. What is the change in entropy of the ice? The latent heat of melting of ice is 80 cal/g.

A. 14.7 cal/K

B. 4000 cal

C. 0.18 g/K

D. 109 cal·K

E. 0.29 cal/(g·K)

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