Review

At which time interval on the graph is the object moving at a constant velocity?

• 0 to 6 seconds

• 0 to 14 seconds

• 6 to 8 seconds

• 8 to 14 seconds

Using the table, who had the slowest average speed?

• Tina

• Jose

• Jake

• Mary

Which car has the greatest magnitude of acceleration during the time interval 10. seconds to 15 seconds?

• W

• X

• Y

• Z

The speed limit for an average city road is 45 miles per hour, or about 72 kilometers per hour. Which animals would receive a speeding ticket if they traveled down the road at their average speed?

• antelope, cheetah, and gray fox

• antelope, cheetah, and gazelle

• giraffe, gray fox, and rabbit

• gazelle, giraffe, and rabbit

A force of 6.0 N is applied horizontally to a 3.0 kg crate initially at rest on a horizontal frictionless surface. After the crate is pushed for 1.5 seconds, it has a velocity of 3.0 m/s. Does this support Newton's second law of motion, that force equals mass times acceleration? Explain

• Yes, because the acceleration of the crate is 2.0 m/s2.

• Yes, because the mass and the velocity of the crate are equal.

• No, because the acceleration of the crate is 2.0 m/s2.

• No, because the mass and the velocity of the crate are equal.

Explain how the results support Newton's first law, which states that an object will remain at rest or in uniform motion in a straight line unless acted upon by an external force.

• The results support the idea that frictional force is what causes the ball to change direction. Without the frictional force acting on the ball, the ball would be able to keep rolling.

• The results support the idea that frictional force is what causes the ball to change direction. Without the frictional force acting on the ball, the ball would not be able to start rolling.

• The results support the idea that frictional force is what causes the ball to slow and come to a stop. Without the frictional force acting on the ball, the ball would be able to keep rolling.

• The results support the idea that frictional force is what causes the ball to begin rolling. Without the frictional force acting on the ball, the ball would not be able to start rolling.

The boat moves forward due to

• a forward thrust from the propeller that is equal to the backward force of the water current.

• a forward thrust from the propeller that is greater than the backward force of the water current.

• a backward thrust from the propeller against the water that is less than the force of gravity.

• a backward thrust from the propeller against the water that is greater than the force of gravity.

Which of the following relationships is true?

• The force of the spheres decrease as the mass of the spheres increase.

• The acceleration of the spheres is constant, even when the mass and force change.

• The mass and force of the spheres will remain constant if their acceleration is constant.

• For each additional kilogram of mass, the force of the sphere doubles.

The inclined plane has a mechanical advantage of 1.5. What is the length, x, of the inclined plane?

• 9.0 feet

• 7.5 feet

• 2.5 feet

• 0.25 feet

What is the mechanical advantage of this system?

• 2

• 3

• 6

• 4