13 What causes falling objects to speed up as they fall?
A force B Friction
C: gravity
D. maginot occurs when surfaces touch each other
14 Which of the following is NOT an example of friction as a helpful force?
A Uning a scrub brush to wash dishes, C Using a cloth to clean a pair of glasses
Using your hand to wave hello to a friend D. Using a marker to draw a picture on a paper
15 Pushing and pulling is an example of
A force B. gravily
O speed
D work