Choose the correct description to go with this work-energy diagram.

• A girl on a sled starts from rest and slides from the top of a hill to the bottom of the hill. System is girl only. Neglect friction. Click here to choose this answer.
• A football player kicks a ball for an extra point. System is the ball and the Earth, from just before the kick to the moment the ball passes through the goal posts. Neglect air resistance. Click here to choose this answer..
• A ski lift lifts a rider from the bottom of the hill to the top of the hill at a constant speed. System is the rider + the Earth. Click here to choose this answer.
• A golf ball is rolling up a gentle slope, slowing down as it goes. System is ball + earth. Neglect rolling friction. Click here to choose this answer.
• A skydiver falls the last 100 m before opening his parachute at a constant speed. System is skydiver and atmosphere, but not the earth below. Click here to choose this answer.