1. A 45 kg block is at rest on a 40^oslope. A force of 430 N is acting on the block up the slope parallel to it. The block does not slide up the slope, what is the minimum value of the coefficient of static friction between the block and the slope?

a. 0.528

b. 0.786

*c. 0.273

d. 0.205

2. A force of 40 N is applied at an angle of 30^oabove the horizon to a 5 kg block that is at rest on a rough horizontal surface. After the block starts to move with an acceleration of 3 m/s², what is the coefficient of kinetic friction between the block and the horizontal surface?

*a. 0.28

b. 0.21

c. 0.31

d. 0.24

e. 0.12

3. When a block is pushed against a vertical wall with a force F, what value of the force must be applied to prevent the 3.0-kg block in the diagram below from sliding down the wall?

a. 5 N

b. 10 N

c. 25 N

*d. 50 N

e. 75 N

4. A cord which goes vertically to a pulley is hooked to a 2 kg mass that rests on the floor. A second mass is attached to the other end of the cord and released. If the 2 kg mass rises 25 cm in 1/3 s, what is the mass of the weight?

a. 2.5 kg

b. 2.7 kg

c. 3.5 kg

*d. 4.6 kg

5. A 200 kg mass is suspended at rest by two cables. The first cable is horizontal and the second makes an angle of 153^owith the first cable. Find the tension of the second cable.

*a. 4322 N

b. 2202 N

c. 441 N

d. 224 N

6. A 2 kg block has an initial velocity of 5.00 m/s as it starts sliding up a 30º inclined plane. How far up the inclined plane does the block slide before it stops?

a. 1.27 m

b. 1.63 m

*c. 2.55 m

d. 2.16 m 

7. A 10.2 kg box is held in place on a smooth ramp by a rope parallel to the slope and attached to a stake at the top of the ramp. What is the tension in the rope if the angle of inclination of the ramp is 35^o?

a. 74.5 N

b. 82.4 N

c. 41.2 N

*d. 57.4 N

8. A 2 kg block has an initial velocity of 5.00 m/s as it starts sliding up a 30º inclined plane. How far will the block travel if the surface is rough and the coefficient of kinetic friction between the block and the ramp is .

a. 0.93 m

b. 1.34 m

c. 1.63 m

*d. 1.89 m

9. If horizontal force moves a crate across the floor and another force at an angle above the horizontal is applied, the force of kinetic friction:

a. decreases

*b. increases

c. does not change

d. has no effect

10. Two masses, m1 = 5 kg and m2 = 30kg, are connected by rope over a frictionless pulley. This device is known as an Atwood machine. What is the acceleration of each mass if the rope is mass less?

a. 6.0 m/s²

b. 5.0 m/s²

c. 4.0 m/s²

*d. 7.0 m/s²

11. A 20 kg crate is resting on a horizontal surface and a force that is 30º above the horizontal is applied. What minimum force is required to start the crate moving if the coefficient of static friction is 0.30?

*a. 82 N

b. 59 N

c. 54 N

d. 56 N

e. 71 N

12. A rope exerts a force of 35 N at an angle of 35^oabove the horizon on a 35 kg crate being pulled across the floor. Find the normal force exerted by the floor.

a. 15 N

*b. 323 N

c. 343 N

d. 35 N

13. In the figure shown, a force of 14 N is applied on block A. What force does B exert on A? (assume the table is frictionless)

a. 6 N

b. 8 N

c. 10 N

*d. 14 N