Kinetic energy and Work
1) What is your kinetic energy, if you run 3 m/s?
2) You let a stone of 40 grams fall 10 meters from the roof. Then it hits the ground.
a) What is the potential energy of the stone, when you let it fall?
b) Ignoring friction, what is the Kinetic energy of the stone, just before it hits the ground?
c) How fast is the stone, just before it hits the ground?
3) A rather confused elephant falls from a cliff. Right now, it falls with 5 m/s, having a kinetic energy of 56250 J. What is the mass of the elephant?
4) John kicks a football that has a mass of 500 grams. His foot touches the football over a distance of 10 cm. The ball now moves with 6 m/s.
a) What is the kinetic energy of the ball after it has been kicked?
b) What work does the force from Johns foot do?
c) How large is the average force tha John applies?