Energy transformations

What is the force needed to give a 20 kg object starting at rest a kinetic energy of 400 Joules after a distance of pushing it 4 meters?

• 100 N

• 5 N

• 800 N

• 20 N

What is the height you need to lift a 20 kg rock to give it 1000 J of potential energy?

• 5 m

• 50 m

• 25 m

• 10 m

If a 30 kg rock had 6000 J of potential energy, what is the kinetic energy of the rock it fell 20 m just before it hits the ground?

• 6000 J

• 10 J

• 200 J

• 300 J

What would be the kinetic energy of a 2 kg rock that was thrown at 30 m/s?

• 900 J

• 225 J

• 120 J

• 450 J

What is the potential energy of a 3 kg cat that is about to jump from a 30 m tall tree?

• 90 J

• 9 J

• 900 J

• 9000 J

What is the work done on lifting a 4 kg dog 15 meters up with a pulley system?

• 600 J

• 60 J

• 3.75 J

• 37.5 J

What is the speed a 250 kg giraffe with a kinetic energy of 800 J?

• 6.4 m/s

• 2.53 m/s

• 3.2 m/s

• 12.8 m/s

What is the efficiency of a ramp that raised a 20 kg box 3 m while pushing the box 100 N of force a distance of 7 m?

• 78.34 %

• 46.56 %

• 85.71 %

• 100 %

What is the mass of a big truck that has 230000 J of kinetic energy that is going 15 m/s?

• 2044.44 kg

• 1022.22 kg

• 30666.67 kg

• 15333.33 kg

What is the height you need to drop a 5 kg water balloon to give it 250 J of kinetic energy?

• 5 m

• 10 m

• 50 m

• 15 m