1. Josie and Kirsty are arguing about how a water rocket water lifts off.

Dave knows that what Josie says isn’t true, but Kirsty has not provided an actual explanation either.

Dave reminds Kirsty about Newton’s Third Law and they both go back and offer an explanation to Josie.

Copy and complete what they say to Josie.

“OK Josie, this is to do with Newton’s Third Law. The rocket pushes the water _ _ _ _ _ _ _ _ _ and the _ _ _ _ _ pushes the rocket _ _ _ _ _ _ _ with an _ _ _ _ _ sized force “. It has nothing to do with the _ _ _ _ _ pushing on the ground.

2. Show how gravitational field strength and acceleration due to gravity are equivalent.

3. A student drops a football from above her head. It lands on the ground 0.63 seconds after being dropped. Calculate the velocity of the ball at the instant it strikes the ground. Assume that air resistance is negligible.

4. An astronaut drops a hammer on the Moon where the gravitational field strength is 1.6 N/kg.
The hammer lands on the surface of the Moon 2.1 seconds after being dropped.

a. Show that the hammer strikes the surface of the Moon with a velocity of 3.36 m/s.
b. Draw a velocity-time graph for the hammer as it falls.

Use the graph to calculate the height that the hammer was dropped from.