A boy weighing kilograms is riding a skateboard. He's moving at 2 meters/second and has 40 joules of kinetic energy. He doubles his speed when he sees his friends ahead of him. His kinetic energy at the faster speed is 80 joules. How much does the bo weigh

Question

Khloe Lewis

Chemistry

11 July, 10:28

A boy weighing kilograms is riding a skateboard. He's moving at 2 meters/second and has 40 joules of kinetic energy. He doubles his speed when he sees his friends ahead of him. His kinetic energy at the faster speed is 80 joules. How much does the bo weigh

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Answers (2)

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Keagan · Answer 1

Kinetic energy = (1/2) * mass*speed^2

substituting given values ...

40 = (0.5) * mass * 2 ... mass = 40Kg

To verify:

speed double = 4m/s

80 = (0.5) * mass * 4 ... mass = (80*2) : 4 = 40 Kg

the mass of the boy is 40Kg

Jacob Stanley · Answer 2

The first one is 20 then the second one is 160

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