Physics Problems: Friction and Acceleration, Exercises of Engineering Physics

Download Physics Problems: Friction and Acceleration and more Exercises Engineering Physics in PDF only on Docsity!

1. To the east
2. To the west
3. There is no friction because the box is at rest with respect to the pickup truck bed
4. Not enough information is given to answer the question

A box is placed in the center of the bed of a pickup truck. As the truck accelerates to the east, the box moves with it, not sliding in the pickup truck bed. In what direction is the friction force exerted by the bed of the truck on the box?

1. 4.

2. 1.

3. 0.

4. 0.

5. 0.

The world record for a dragster for a standing quarter-mile (402. m) is 4.428 seconds as of Sept 15, 2008. That is, the dragster started from rest and covered a distance of 402.3 meters in only 4.428 sec- onds. Let’s neglect air friction and assume that the acceleration was constant. Given: g = 9.8 m/s^2. What was the coefficient of kinetic friction?

1. 8.4 m/s^2
2. 5.9 m/s^2
3. 2.5 m/s^2
4. 1.4 m/s^2
5. 20.9 m/s^2

Two boxes, one with mass 22 kg and the other with mass 33 kg, are connected by a rope and slide on a horizontal plane. The 33 kg box is pulled by a horizontal rope that exerts a force of 460 N. The coef- ficient of kinetic friction is μk = 0.6 between each box and the plane’s surface. What is the acceleration of the boxes?

1. 8.4 m/s^2
2. 5.9 m/s^2
3. 2.5 m/s^2
4. 1.4 m/s^2
5. 20.9 m/s^2

Two boxes, one with mass 22 kg and the other with mass 33 kg, are connected by a rope and slide on a horizontal plane. The 33 kg box is pulled by a horizontal rope that exerts a force of 460 N. The coef- ficient of kinetic friction is μk = 0.6 between each box and the plane’s surface. What is the acceleration of the boxes?

1. 20.9 N

2. 447 N

3. 11.1 N

4. 185 N

5. 74.3 N

What is the tension on the rope between the two boxes?

1. slows down.
2. moves at uniform speed.
3. speeds up.
4. none of the above.

An object is held in place by friction on an inclined surface. The angle of inclination is increased until the object starts moving. If the surface is kept at this angle, the object

1. μk=(-a - gsinθ)/(gsinθ)

2. μk= (a -gsinθ)/(gcosθ)

3. μk= (gsinθ-a)/(gcosθ)

4. μk= (gcosθ-a)/(gcosθ)

5. μk= (a - gsinθ)/(gsinθ)

A block accelerates down a frictional inclined plane that is at an angle θ with respect to the horizontal. Choose the x-axis to be positive up along the plane (so a < 0).

Draw and label a free body diagram.

What is the correct expression for the coefficient of kinetic friction μk?