b. friction c. force d. gravity 1. Which force is cerised by two faces rubbing together? a. Gravity 2. force pulls down anything towards the earth. a. Gravitational b. frictional C. air resistance 3. What makes a rolling ball slow down and stop? a. Air resistance c. friction b Brake 4. How is brake useful? a. It uses friction to slow down a moving Vehicle. b. It uses friction to make vehicles move faster. c. It uses friction to move the vehicle to any direction . d. It uses friction to move the vehicle easily. 5. Why is parachute important to a sky diver? a. It directs his motion. b. It makes him fall faster. c. It keeps him appear beautiful as he falls down d. It slows down his motion to have safe landing. 6. What force do the brakes on a bicycle produce to stop the bike? a. gravity b. pitch c. friction d. magnetism
