# [SOLVED] Help with basic physics problem on kinetic energy?

Help with basic physics problem on kinetic energy?

A mother has four times the mass of her young son. Both are running with the same kinetic energy.

What is the ratio [vs/vm] other of their speeds?

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## The Best answer for Help with basic physics problem on kinetic energy?

mass of mother = 4 mass of sun

mothers KE

0.5( 4 m) vm^2

sons KE

0.5( m) vs^2

their KE are equal

0.5( 4 m) vm^2 = 0.5( m) vs^2

solve for vs / vm

vs^2/ vm^2 = 4

vs/vm = sqrt 4

vs/vm =2.0

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If you consider the sons mass as m then the mothers mass is 4m. KE=1/2 mv^2. so moms kinetic energy is 2MVm^2 and sons is 1/2MVs^2.They are equal so Vs^2/Vm^2=4

Vs/Vm=2 thus the ratio is 2:1 that is 2.0

i think this is the correct answer Help with basic physics problem on kinetic energy?
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55mile/h = fifty 5 *1609.3/3600 m/s = 24.586 m/s 67mile/h = sixty seven*1609.3/3600 m/s = 29.ninety 5 m/s W = a million/2 * m * (v^2 - u^2)=a million/2 * m * (29.ninety 5^2 - 24.586^2) F * S = a million/2 * m * (897 - 604.5) m * g * S = a million/2 * m * 292.5 S = 146.25/10 = 14.625 m
Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat.