Just as a skydiver steps out of a helicopter, someone who’s watching starts a stopwatch. So the time is zero as the skydiver steps out of the plane. What is the skydiver downward velocity at that instant just before starting to fall?

Within a pendulum, as potential energy decreases, energy increases. a. heat b. kinetic c. frictional d. gravitational

The experiment done in lab is repeated, using a ball that has unknown mass m. you plot your data in the form of f 2 versus m/l, with f in rev/s, m in kg, and l in m. your data falls close to a straight line that has slope 3.19 m/(kg · s2). use g = 9.80 m/s2 and calculate the mass m of the ball.

1. explain how you calculate the net force in any direction on the box. 2. suppose an upward force of 15n is added to the box. what will be the net vertical force on the box? 3. what force could be applied to the box to make the net force in the horizontal direction zero? explain. 4. suppose a force of 25n to the right is added to the box. what will be the net force to the right?