Forces and motion

A dog runs for 2 seconds without stopping. After 1 second, the dog travels 6 meters. By the end of the next second, the dog has traveled an additional 4 meters. Which best describes the motion of the dog during the two seconds?

• The dog slows down.

• The dog speeds up.

• The dog moves with a constant speed.

• The dog changes directions.

Which best describes how the average speed is different from constant speed?

• Average speed is the total distance traveled divided by total time regardless of the speed at any given time; constant speed never changes.

• Average speed never changes; constant speed is the total distance traveled divided by total time regardless of the speed at any given time.

• Average speed is total time divided by distance traveled; constant speed never changes.

• Average speed never changes; constant speed is total time divided by total distance.

Which best describes the change in position of an object’s location compared to a reference point?

• acceleration

• motion

• speed

• vector

A man was pedaling a bicycle at an average speed of 5 miles per hour. After 3 hours, how far had the man traveled? (speed = distance ÷ time)

• 2 miles

• 5 miles

• 8 miles

• 15 miles

The BEST example of balanced forces is a

• car increasing speed

• bus parked in a garage

• ball kicked along a flat surface

• roller coaster slowing down on an incline.

Which statement BEST explains why a car that is rolling on a level surface will eventually come to a stop?

• Frictional forces oppose the motion of the car.

• Forward motion slowly runs out as energy is expended.

• The natural state of an object is to be at rest.

• Inertia acting on an object will dissipate.

The motion of a toy car is shown in the graph.

In which section of the graph is the car moving away from its starting point?

• W

• X

• Y

• Z

Which effect would the rough surface have on a box that is pulled along the sidewalk?

• It would reduce the amount of work that is performed when pulling the box.

• It would oppose the force that is being applied to the box when it is pulled.

• It would decrease the resistance between the forces that are pulling the box.

• It would help reduce the force of gravity when the box is pulled.

A toy robot moved from a starting point, traveling in a straight line at different speeds and then turning around and returning to the starting point at different speeds.

What is the total distance that the toy robot traveled?

• 12 m

• 24 m

• 48 m

• 96 m

Mimi pushes a book from the edge of a table and releases it at Point 1. It slides across the table and stops at Point 2.

Which statement BEST explains the forces that act on the book as it slides across the table?

• The friction force increases between Point 1 and Point 2.

• The friction force decreases momentum between Point 1 and Point 2.

• The force applied from the push decreases between Point 1 and Point 2.

• The pushing force starts at Point 1 and the friction force stops at Point 2.