Force equals —

A. speed times acceleration
Incorrect. This is not the formula for force.

B. mass plus speed
Incorrect. This is not the formula for force.

C. mass times speed
Incorrect. This is not the formula for force.

D. mass times acceleration
Correct! F=ma is the formula for force.

Which of the following choices best completes the statement below?

Unbalanced forces cause a change in an object’s

1. mass
2. speed
3. direction
4. velocity

A. I and III
Incorrect. Unbalanced forces do not change an objects mass.

B. I, II, and III
Incorrect. Unbalanced forces do change an objects speed and direction but since velocity is the speed and direction an object is moving it is also changed.

C. II, III, and IV
Correct! Unbalanced forces change an objects speed and direction. Since velocity is the speed and direction an object is moving it is also changed.

D. All of the above
Incorrect. Unbalanced forces do not change an objects mass.

Use the diagram below to answer the question.

What is the resulting net force?

A. 205 N to the left
Incorrect. The forces are opposite forces so you need to subtract the two forces.

B. 155 N to the left
Correct!

C. 155 N to the right
Incorrect. The net force is correct but not the direction. The object will move toward the direction with the greater force.

D. 205 N to the right
Incorrect. The forces are opposite forces so you need to subtract the two forces.

A construction worker drops his hammer off the roof of a house. The hammer has a mass of 9kg, and gravity accelerates it at 9.8 m/s² How much force does the earth apply to the hammer?

A. 88.2 N
Correct!

B. .918 N
Incorrect. The formula for force is F=ma. Force= mass X acceleration.

C. .8 N
Incorrect. The formula for force is F=ma. Force= mass X acceleration.

D. 18.8 N
Incorrect. The formula for force is F=ma. Force= mass X acceleration.

Your bicycle has a mass of 9.1 kilograms.You accelerate at a rate of 1.79 m/s². Calculate the net force that is accelerating the bicycle.

A. 5.083 N
Incorrect. The formula for force is F=ma. Force= mass X acceleration.

B. 10.908 N
Incorrect. The formula for force is F=ma. Force= mass X acceleration.

C. 16.289 N
Correct!

D. 7.390 N
Incorrect. The formula for force is F=ma. Force= mass X acceleration.