Asled and rider with a combined mass of 140 kg are at the top of a hill of height 12.5 m above the level ground below. the sled is given a push providing an initial kinetic energy of 1550 j at the top of the hill. choosing a reference level at the bottom of the hill, what is the potential energy of the sled and rider at the top of the hill?

Waves that cause the most damage during an earthquake are a. surface waves c. s waves b. p waves d. ocean waves

As you are trying to move a heavy box of mass m, you realize that it is too heavy for you to lift by yourself. there is no one around to , so you attach an ideal pulley to the box and a massless rope to the ceiling, which you wrap around the pulley. you pull up on the rope to lift the box. use g for the magnitude of the acceleration due to gravity and neglect friction forces. once you have pulled hard enough to start the box moving upward, what is the magnitude f of the upward force you must apply to the rope to start raising the box with constant velocity? express the magnitude of the force in terms of m, the mass of the box.

You've already seen the value of 9.8 in this lesson. what's this value called? what quantity does it represent?