Question

An 80 kg skateboarder moving at 3 m/s pushes off with her back foot to move faster. If her velocity increases to 5 m/s, what is her change in kinetic energy as a result? J How much work did she perform? J

Answer 1

It's 640 for both answers. :)

Answer 2

640 J

Step-by-step explanation:

ΔKE = KE − KE₀

ΔKE = ½ mv² − ½ mv₀²

ΔKE = ½ m (v² − v₀²)

ΔKE = ½ (80 kg) ((5 m/s)² − (3 m/s)²)

ΔKE = 640 J

Her kinetic energy increases by 640 J, so she does 640 J of work.