Newton's first law states that an object in motion will stay in motion unless acted upon by an unbalanced force. If you roll a ball across the floor, you put the ball in motion, but after time, the ball stops. Does this violate Newton's first law?

Leah watches a toy car move across a table at a constant speed. The car moves across the table in one direction and falls off the other side. Leah decides to try another situation. She watches the car move across the table at a constant speed, then when it reaches the other side of the table, her friend Joey pushes the car in the other direction. The car moves back to Leah. Based on Leah's informal experiment, what forces cause the car to change direction?

A ball is dropped from a tower. From whose reference point is the ball approaching the observer?

Sandy puts a paper clip on the table and puts a magnet near the paper clip. The paper clip begins to move. What type of forces are acting on the paper clip?

_______ can be generally defined as a change in position.

A book is sitting on a table at rest. Which of the following best describes the forces acting on the book?

Steve and Barry are racing each other, and Barry is winning. If Barry is moving faster than Steve, from which reference point is Barry's position increasing through time?

Gravity should make the rock slide down the hill. What force is acting to balance gravity, keeping the rock in place?

An object has balanced forces acting on it. Which of the following describes the result these balanced forces have on the object?

A train is speeding down a railroad track at a speed of 50 miles per hour. From whose reference point is the train not moving?

Bryan and Alyssa are playing tug-of-war against Daniel and Maria. Bryan and Alyssa are exerting a combined force of 10 N. Daniel and Maria are exerting 12 N of force. Which of the following has resulted?

Last-minute Louis frantically tried to finish his homework while his mom drove him to school. He placed his book on his lap and was reaching for a pencil when his mom suddenly slammed on the brakes. Although Louis stayed buckled in his seat, his book flew forward and crashed into the front windshield. Which of the following was most responsible for the book flying forward?

It is 10:00 in the morning, and Wendy is late for school. She is currently running north at a speed of 5 meters per second and is 2 miles south of her school. Which of the following best describes Wendy's current position?

Which of the following situations demonstrates balanced forces?

Melinda and Bart are sitting beside each other in the third car of a roller coaster. From whose reference point are Melinda and Bart moving away from the observer?

Barry knocks a baseball into the air with his bat. Shortly after the ball is hit, it is traveling at 25 m/s to the east and parallel to the ground. After two seconds, the ball is 50 meters to the east of Barry. Which of the following best describes the ball's direction of motion?

If an object is moving at a constant speed in one direction, what is needed to change its speed or direction?

_______ measures an object's change in position per unit time.