Physics final (2)

A bicycle wheel of radius 0.70m is rolling without slipping on a horizontal surface with an angular speed of 2.0 rev/s when the cyclist begins to uniformly apply the brakes. the bicycle stops in 5.0. How far did the bicycle travel during the 5.0 s of braking? A) 1.8m B) 8.8m C) 22m D) 42m E) 44m

22m

A 3.0kg ball and a 1.0kg ball are placed at opposite ends of a massless beam so that the system is in equilibrium as shown. What is the value of the ratio of the lengths, b/a? A) 2.0 B) 2.5 C) 3.0 D) 4.0 E) 5.0

4.0

Two asteroids are drifting in space with trajectories shown. Assuming the collision at point 0 between them is completely inelastic, at what angle from its original direction is the larger asteroid deflected? A) 80 above the x B) 69 above the x C) 42 above the x D) 47 above the x E) 90 above the x

42 above the x

A 100kg cannon at rest contains a 10kg cannonball. When fired, the cannonball leaves the cannon at a speed of 90 m/s. What is the recoil speed of the cannon? A) 4.5 m/s B) 9 m/s C) 45 m/s D) 90 m/s E) 0 m/s

9 m/s

A fan rotating with an initial angular velocity of 1000 rev/min is switched off. In 2 seconds, the angular velocity decreases to 200 rev/min. Assuming the angular acceleration is constant, how many revolutions does the blade undergo during this time? A) 10 B) 20 C) 100 D) 125 E) 1200

20

A bat strikes a 0.050-kg baseball so that its velocity changes by +32 m/s in 0.080 s. With what average force was the ball struck? A) +20 N B) +300 N C) +150 N D) 15 N E) 300 N

+20N

A wheel with a 0.10m radius is rotating at 35 m/s. It then slows uniformly to 15 rev/s over a 3.0s interval. What is the angular acceleration of a point on the wheel? A) -2.0 rev/s2 B) 0.67 rev/s2 C) -6.7 rev/s2 D) 42 rev/s2 E)-17 rev/s2

-6.7 rev/s2

A 3.0kg cart moving to the right with a speed of 1.0 m/s has a head-on collision with a 5.0kg cart that is initially moving to the left with a speed of 2.0m/s. After the collision, the 3.0kg cart is moving to the left with a speed of 1.0m/s. What is the final velocity of the 5.0kg cart? A) 0m/s B) 0.80 m/s to the right C) 0.80 m/s to the left D) 2.0 m/s to the right E) 2.0 m/s to the left

0.80 m/s to the left

A wrench is used to tighten a nut as shown in the figure. A 12-N force is applied 7.0 cm from the axis of rotation. What is the magnitude of the torque due to the applied force? A) 0.58 N/m B) 0.84 N/m C) 1.71 N/m D) 14 N/m E) 58 N/m

0.84 N/m

A football player kicks a 0.41 kg football initially at rest; and the ball flies through the air. If the kicker's foot was in contact with the ball for 0.051s and the ball's initial speed after the collision is 21 m/s, what was the magnitude of the average force on the football? A) 97N B) 46N C) 81N D) 170N E) 210 N

170N

A bullet of mass m is fired at speed Vo into a wooden block of mass M. The bullet instantaneously comes to rest in the block. The block with the embedded bullet slides along a horizontal surface with a coefficient of kinetic friction u. Which of the following expressions determines how far the block slides before it comes to rest? A) S= mVoˆ2/Mug B) S= m/m+M(Voˆ2/ug) C) S=(m/m+M)ˆ2 x Voˆ2/2ug D) S= (m/m+M)ˆ2 x √Vo2/2ug E) S= Voˆ2/ug

S=(m/m+M)ˆ2 x Voˆ2/2ug

momentum will be conserved in a two-body collision only if A) Both bodies come to rest B) The collision is perfectly elastic C) The kinetic energy of the system is conserved D) The net external force acting on the two-body system is zero E) The internal forces of the two body system cancel in action-reaction pairs.

The net external force acting on the two-body system is zero

An object of mass 3, initially at rest, explodes breaking into two fragments of mass m and 2m, respectively. Which one of the following statements concerning the fragments after the explosion is true? A) They will fly off at right angles B) They will fly off in the same direction C) The smaller fragment will have twice the speed of the larger fragment D) The larger fragment will have twice the speed of the smaller fragment E) The smaller fragment will have four times the speed of the larger fragment

The smaller fragment will have twice the speed of the larger fragment

A rigid body rotates about a fixed axis with a constant angular acceleration. Which one of the following statements is true concerning the tangential acceleration of any point on the body? A) The tan. acceleration is zero m/s2 B) The tan. acceleration depends on the angular velocity C) The tan. acceleration is equal to the centri. acceleration D) The tan. acceleration is constant in both magnitude and direction E) The tan. acceleration depends on the change in the angular velocity.

The tan. acceleration depends on the change in the angular velocity.

Complete the following statement: When a net torque is applied to a rigid object, it always produces a A) constant acceleration B) rotational equilibrium C) constant angular velocity D) constant angular momentum E) change in angular velocity

change in angular velocity