# Gravity and freefall

Instructions: answer the questions, check them carefully, and when you are sure they are all right, press submit. The number of correct answers will be displayed.

Question 1: If it takes a hammer 1.0 second to fall \$5\$ metres on Earth, how long does it take to fall the same distance on the Moon?

Question 2: Approximately how fast is a heavy ball travelling after 4 seconds of freefall?

Question 3: A falling object accelerates at about 10 m/s2 if we ignore air resistance. How fast do you have to throw a ball upwards for it to take 3 seconds before you catch it again?

Question 4: A rifle can fire a bullet at 900 m/s. Ignoring air resistance, how long would the bullet stay in the air if it is fired straight up?

Question 5: Astronaut David Scott dropped a hammer and a feather on the Moon. What did this demonstrate?

Question 6: How many fundamental forces are there?

Question 7: A skier makes a jump as shown in the photo. What shape is his flight?

Question 8: A rocket accelerates upwards at 20 m/s2 for 8 seconds. How high is it?

Question 9: When a parachutist freefalls and opens his chute, the force of gravity on him

Question 10: When a parachutist freefalls and opens his chute, his velocity

Question 11: A ball follows the shape of a parabola when it bounces. What are the vertical and horizontal components of its motion:

Question 12: A boy throws a ball straight up into the air. The time the ball takes to reach the top of its flight...

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Question: A smooth, heavy steel ball is droppd from rest. After \$t_1\$s it passes point X, after \$t_2\$s it passes point Y. The distance \$h\$ is the distance between X and Y. What is the acceleration of free fall?

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