WCAS - Washington Comprehensive Assessment of Science Motion and Stability: Forces Questions and Answers

Question 1

A student pushes a heavy box across a rough floor. The box moves at a constant velocity. Which of the following statements BEST describes the forces acting on the box?

Accepted Answer

The force of friction is equal to the force of the push.

Answer

The force of the push is greater than the force of friction.

Answer

The force of gravity is greater than the force of the push.

Answer

The net force on the box is in the direction of motion.

Question 2

A rocket accelerates upward from a launchpad. According to Newton's Third Law of Motion, what is the 'reaction' force to the hot gases pushing downward from the rocket's engine?

Accepted Answer

The hot gases pushing up on the rocket.

Answer

The rocket pushing down on the launchpad.

Answer

The force of gravity pulling the rocket down.

Answer

The air resistance pushing against the rocket.

Question 3

Two identical carts, Cart A and Cart B, are at rest on a frictionless surface. A student applies a force of 10 Newtons to Cart A and a force of 20 Newtons to Cart B for the same amount of time. Which of the following will be true?

Accepted Answer

Cart B will have a greater change in motion than Cart A.

Answer

Cart A will have a greater change in motion than Cart B.

Answer

Both carts will have the same change in motion.

Answer

Neither cart will experience a change in motion.

Question 4

A book is sitting motionless on a horizontal table. Which of the following correctly identifies an action-reaction pair of forces?

Accepted Answer

The force of the book pushing down on the table and the force of the table pushing up on the book.

Answer

The force of the table pushing up on the book and the force of gravity pulling down on the book.

Answer

The force of the book pushing down on the table and the force of gravity pulling down on the book.

Answer

The force of the Earth pulling down on the book and the force of the table pushing up on the book.

Question 5

Which scenario provides evidence that an unbalanced force is acting on an object?

Accepted Answer

A satellite orbiting Earth at a constant speed.

Answer

A car traveling at a constant speed of 60 mph on a straight highway.

Answer

A tug-of-war game where the rope does not move.

Answer

A soccer ball sitting motionless on the grass.

Question 6

A student is designing an experiment to investigate how the mass of an object affects its change in motion when a constant force is applied. What are the independent and dependent variables in this investigation?

Accepted Answer

Independent: mass of the object; Dependent: change in motion (acceleration).

Answer

Independent: applied force; Dependent: mass of the object.

Answer

Independent: change in motion (acceleration); Dependent: mass of the object.

Answer

Independent: surface friction; Dependent: applied force.