Laws of Motion

Which of the following is an example of a noncontact force?

• Musician playing piano

• Athlete hitting a ball with a bat

• A ball falling after you toss it in the air

• Karate expert breaking a stack of wood

An object's weight is ______ its mass.

• equal to

• less than

• proportional to

• greater than

The unit of force is ______.

• m/s

• hertz

• joule

• newton

Which of the following is an example of an unbalanced force?

• a book sitting on a table

• car sitting in the garage

• person on an elevator going down

• person leaning on a wall

Forces that are equal in size but opposite in direction are ______.

• balanced forces

• frictional forces

• inertial forces

• net forces

When two birds are pulling on a worm and the worm moves toward the first bird, you know that the forces are _____.

• long-range

• action-reaction

• unbalanced

• balanced

Unbalanced forces can make an object accelerate by ______.

• changing its speed

• changing its direction

• both the above answers

• none of the above answers

The relationship among force, mass, and acceleration is stated in _______.

• the law of conservation of momentum

• newton's first law of motion

• newton's second law of motion

• newton's third law of motion

A 3,000 N force gives an object on acceleration of 15 m/s2. The mass of the object is ______.

• 45,000 kg

• 200 kg

• 1,500 kg

• 15 kg

a 300-N force acts on a 25 kg object. The acceleration of the object is ______

• 7,500 m/s/s

• 300 m/s/s

• 25 m/s/s

• 12 m/s/s