Physics Week 4 Multiple Problems. 1. A rail car of mass 4500 kg is moving with a velocity of 12.4 m/s collides with a stationary rail car of mass 6700 kg. What is the velocity of the two cars if they stick after they collide?

2. A tennis player hits a 1.45 kg tennis ball with a racket of mass 2.5 kg. If he hits the ball with a velocity of 7.5 m/s and then stops, what impulse did he imply on the ball? What is the ball’s velocity?

3. A 35 g bullet is fired in a ballistic pendulum device (see page 178 In text) and increases the height of the center of mass of the device and the bullet by 2.1 cm. If the level arm has a mass of 3.4 kg, what was the initial velocity of the bullet?

4. A puck slides on a surface for 5.6 m before it stops. If it was moving at a velocity of 15 m/s and has a mass of 1.2 kg, what is the force of friction exerted on the puck? There is a non-conservative work done on the puck equal to the change in kinetic energy, or:

5. If a tire on a semi-truck is 1.1 m. How many FULL rotations will the tire roll if the truck moves 24.5 meters?

6. A large circus ride has a centripetal acceleration at 6.0 m/s2. If the circular ride has a radius of 11.0 m, what is its velocity at the edge?

7. If a 56 diameter circular disk is uniformly angularly accelerating at a rate of 5.0 rad/s2, what will the final angular velocity be after 4.0 seconds if it starts at a rate of 10.0 rad/s? What angle is subtended over that time?

8. A 40.0 N force is applied to a 46.0 cm long torque wrench. What is the net torque applied to the nut? Also if this force is applied for 3.0 seconds and the bolt starts from rest and ends with an angular velocity of 0.5 rad/s, what is the bolt’s moment of inertia?

1. A car uniformly decelerates at a rate of -5.00 m/s2. How far does the car travel after 1.50 seconds if it initially was moving at a speed of 25.0 m/s?

A) c. 31.9 m

B) a. 25.0 m

C) b. 37.5 m

D) d. 28.1 m

2. The international space station orbits the Earth at an altitude of about 250 km. What is the acceleration due to gravity at that height above the ground? The mass of the Earth is 5.98 x 1024 kg and the radius of the Earth is 6371 km.

A) b. 0 m/s2

B) c. 9098710 m/s2

C) d. 9.10 m/s2

D) a. 9.8 m/s2

3. Three forces pull on a block, the first is 65 N and in the positive x direction. The second is 65 N in the negative x direction and the third is 45 N and is 90 degrees from the first two forces in the positive y direction. What can you say about the resultant force?

A) a. The resultant force is zero.

B) d. The resultant force is 65 N and in the negative y direction.

C) c. The resultant force is 45 N and in the negative y direction.

D) b. The resultant force is 45 N and in the positive y direction.

4. A 25 kg is acted on by a 45 N horizontal force. If the box accelerates at a rate of .75 m/s2, what is the coefficient of kinetic friction between the box and the table?

A) b. 0.11

B) c. 0.55

C) a. 0.25

D) d. 1.05

Free-body diagram:

5. A block is at the top of a ramp that is 4.5 m above a table. If the block slides without friction, how fast is it going at the bottom of the ramp?

A) a. 9.4 m/s

B) d. 3.6 m/s

C) c. 0.0 m/s

D) b. 4.5 m/s

6. A 7.93 kg box is pulled along a horizontal surface by a force FP of 84.0 N applied at a 47.0º angle. If the coefficient of kinetic friction is 0.35, what is the acceleration of the box?

Free Body Diagram:

7. A cannonball is fired horizontally with an initial velocity of 655 m/s from the end of a cliff 725 m high. How far in the x direction does the cannonball in the air before it hits the ground?

A) c. 5670 m

B) a. 7960 m

C) b. 4030 m

D) d. 9540 m

8. A subatomic particle with mass m initially at rest suddenly decays. If one of the resultant particles with mass 0.40 m of mass leaves with a velocity of 5.5 x 105 m/s, what is the velocity of the other particle created?

A) 2.5 x 105 m/s

B) 3.7 x 105 m/s

C) 3.3 x 105 m/s

D) 6.0 x 105 m/s