PHYS1224 : Spring 2006

Exam #2 - Part B

Name: ______

Problem 1:______(20)

Problem 2:______(20)

Problem 3:______(35)

Problem 4:______(30)

Problem 5:______(30)

Problem 6:______(20)

Problem 7:______(30)

Problem 8:______(30)

Problem 9:______(20)

Total Part B :______(235)

1.You push your physics book 1.40 m along a horizontal table top with a horizontal force of 2.90 N. The opposing force of friction is 0.597N.

A.How much work does your 2.90 N force do on the book?

B.What is the total work done on the book by the friction force?

C.What is the change in the kinetic energy of your physics book?

2.The figure below gives the angular speed versus time for a thin rod

that rotates around one end. The vertical axis is marked in increments of 2 rad/s.


A.What is the magnitude of the rod's angular acceleration?

B.At t = 4.0 s, the rod has a rotational kinetic energy of 1.30 J. What is

its kinetic energy at t = 0?

3.In the Figure, one block has mass M = 510 g, the other has mass

m = 420 g, and the pulley, which is mounted in horizontal frictionless bearings, has a radius of 6.00 cm. The pulley is a uniform pulley of mass 310 g.


A.Draw Free Body Diagrams for both blocks and the pulley.

B.What is the magnitude of the block's acceleration?

3BContinued

C.What is the tension in the part of the cord that supports the heavier block?

D.What is the tension in the part of the cord that supports the lighter block?

E.What is the magnitude of the pulley's angular acceleration?

4.A spring of spring constant 100 N/m is connected to a cylinder of

mass 10.0 kg and radius 0.4 m such that the cylinder can rotate about the center of mass axis. The spring is stretched to a distance 1.2 m and then the system is released from rest as shown below. While answering the following questions assume that the cylinder rolls without slipping.

A)What is the translational speed of the cylinder when it is at the spring's unstretched position?

4.Continued

B)What is the torque that is supplied by the spring with respect to an axis through the cylinder’s instantaneous point of contact when the spring is fully compressed.

5.A 1000-N uniform boom is supported by a cable as shown below. The

boom is pivoted at the bottom, and a 610-N object hangs from its top. Find the tension in the cable and the components of the of the reaction force on the boon by the floor.

5.Continued

6.A diver comes off a board with arms straight up and legs straight

down, giving her a moment of inertia about her rotation axis of

18 kgm2. She then tucks into a small ball, decreasing this moment of inertia to 3.6 kgm2. While tucked, she makes two complete revolutions in 1.0 s. If she hadn’t tucked at all, how many revolutions would she have made in the 1.5 s from board to water?

7. A m = 2.00 kg block is pushed against a spring with negligible mass and force constant k = 300. N/m, compressing it d = 0.250 m. When the block is released, it moves along a frictionless, horizontal surface and then up an incline with slope 37.0 and a coefficient of kinetic friction of 0.320.

A.What is the speed of the block as it slides along the horizontal surface after having left the spring?

B.How far does the object travel up the incline before starting to slide

back down?

8.A 2.4 g bullet is fired into a 24 kg block. The block is connected by

a physics string to the ceiling as part of a ballistic pendulum for determining the muzzle speed of a gun. After the bullet hits the block, the bullet passes through the block at a speed of 100 m/s and the block swings up to a maximum height of 2.75 m as shown below:

A.What is the speed of the bullet just before it hit the block?

8.Continued

B.How much work was done by the block upon the bullet?
9.A 45.0 kg woman stands up in a 60.0 kg canoe of length 5.00 m. She

walks from a point 1.00 m from the left end of the canoe to a point 1.00 m from the right end of the canoe. If resistance to motion of the canoe in the water can be neglected, how far and in what direction does the canoe move during the process.