At which position is the roller coaster car's mechanical energy 100% kinetic energy?

This car has 100 J of potential energy at position A. It has 80 J of potential energy at position D. What is its kinetic energy at position D?

At which position is the roller coaster car's kinetic energy increasing?

A waiter carries a 10 N tray of food from the kitchen to a table of guests (a total of 8 m). How much work did the waiter do on the tray of food while he was walking?

You and I are both downstairs in the Magnet Building, and we need to get to my room. You walk directly up the stairs. It takes you 10 s.

I walk outside, up the hill, around the building by the parking lot, up the stairs by the weight room, in through the door from the cafeteria, and then down the hallway to my room. It takes me 150 s.

When we both finally reach my room, who has more gravitational potential energy?

Lifting a weight will require 20 J of work. Which of the following will result in increased power?

You push a boulder with 25 N of force for 90 s, but the boulder won't move. How much work did you perform on the boulder?

You lift a 100 kg weight above your head in 5 s. Your friend lifts the same weight in 8 s, to the same height. Who used the most power?

You lift a 100 kg weight above your head in 4 s. Your friend lifts a 200 kg weight to the same height, also in 4 s. Who used the most power?

A 90 kg ninja climbs a 30 m tall building in 12 s. What formula will you use to calculate the work done by the ninja?

Sammy the bluebird flies quickly from the ground to a nearby powerline. His mate - Angel, who has the same mass - flies slowly to join him. Who gained the most potential energy?