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

Chemistry

Emilia

3 January, 06:23

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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Gerardo Warren · 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

Jaime Haley · Answer 2

The first one is 20 then the second one is 160

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