1. 
The potential energy (J) [= Mass(kg) x Distance(m) x Acceleration of Gravity(m/s^{2})] of an object on earth depends on its distance from the ground. If you hold a hammer (mass = 1 1/4 kg) 98 cm from the ground, what is its potential energy? The acceleration of gravity is 9.8 m/s^{2}. Hint: The unit for distance must be in meters when calculating potential energy.


2. 
Ashley is riding her bicycle on the hike and bike trail around Village Lake. She rides 35 minutes and travels 9 2/3 miles. She then takes a 15 minutes rest. After resting (and eating an energy bar) she rides another 50 minutes and covers 15 2/3 miles. What was her average speed for the entire trip in miles per hour? (include the time she rested in the answer)


3. 
The acceleration of gravity on planet X is half of that of earth's moon and the gravity on the moon is onesixth that of earth. If a block of wood weighs 16 pounds on earth, what will it weigh on planet X?


4. 
Devin is hiking in the national park. He is on a 6 3/4mile hike and he makes four evenly spaced rest stops along the way. At what mile of the hike does he make his last stop?


5. 
Mr. Bloop is giving a demonstration using two hard rubber balls. He is dropping them from his hands to the floor and measuring the width of the dents they make in a piece of polystyrene foam. The one that has the most kinetic energy when it hits leaves the widest dent. Both balls have a radius of 2 1/2 cm but their masses are different. The red ball is 11 1/3 grams and the blue on is 17 3/4 grams. If the blue one is held 3 2/3 m from the surface of the foam and the red one is held 4 1/2 m up, which one should make the larger dent? You do not need to know the value for the acceleration of gravity to solve this problem!


6. 
The kinetic energy (KE) of an object is onehalf its mass times its velocity squared (1/2 mv^{2}). If a 2 1/2kg ball has a velocity of 2/3 m/s, what is its KE? (hint: don't forget to square the velocity)

