A truck hauling a large load traveled 28 miles in 4 hours It had a maximum speed of 15 mph going downhill and 3 mph going up the hill.The truck had an average speed of square mph.I The marble rolling down the paper ramp did not roll back to the top on the other side of the desk not because of gravity but due to __ , which slowed it down. A track and field athlete is running forward with a javelin at a velocity of 4.2m/s If she throws the javelin at a velocity relative to her at 10.3m/s the velocity of the javelin would be m as it hits square m/s the ground.

1. The average speed of the truck can be calculated by dividing the total distance traveled by the total time taken. In this case, the truck traveled 28 miles in 4 hours, so the average speed is 28 miles / 4 hours = 7 mph.<br /><br />2. The marble rolling down the paper ramp did not roll back to the top on the other side of the desk not because of gravity but due to friction, which slowed it down.<br /><br />3. The velocity of the javelin as it hits the ground can be calculated by adding the velocity of the athlete to the velocity of the javelin relative to her. In this case, the athlete is running forward with a velocity of 4.2 m/s and throws the javelin at a velocity relative to her of 10.3 m/s, so the velocity of the javelin as it hits the ground is 4.2 m/s + 10.3 m/s = 14.5 m/s.