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3 years ago

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A 45.0 kilogram boy is riding a 15.0-kilogram bicycle with a speed of 8.00 meters per second. What is the combined kinetic energ

y of the boy and the bicycle? A)480.J B)240.0J C)1920J D)1440J

1 answer:

svlad2 [7]3 years ago

3 0

Answer:

1920Joules

Explanation:

The formula for calculating the kinetic energy of a body is expressed as;

KE = 1/2 mv²

m isthe mass

V is the speed

For the two masses, the combined KE is expressed as;

KE = 1/2(m1+m2)v²

KE = 1/2(45+15)(8)²

KE = 1/2 * 60 * 64

KE = 30 * 64

KE = 1920J

Hence the combined kinetic energy of the boy and the bicycle is 1920Joules

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valentinak56 [21]

1) The mass of the continent is $2.13\cdot 10^{21} kg$

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3) The speed of the jogger must be 2.76 m/s

Explanation:

1)

The continent is a slab of side 5900 km (so the surface is 5900 x 5900, assuming it is a square) and depth 26 km, therefore its volume is:

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The mass of the continent is given by

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Substituting, we find the mass:

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2)

To find the kinetic energy, we need to convert the speed of the continent into m/s first.

The speed is

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$v=5.08\cdot 10^{-10}m/s$ is the speed

Substituting,

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