Question

Is it reasonable that a 30-kg child could run fast enough to have 100 J of kinetic energy?

(A). Yes, this is reasonable
(B). No, this is not reasonable

Answer 1

A.) Yes, this is reasonable

Step-by-step explanation:

The formula for kinetic energy states
`E_k=(1)/(2)mv^2`:

`E_k=100J\\m=30kg`

Rewrite the formula to solve for v:

`v=\sqrt((2E_k)/(m))\\v=\sqrt(((2)(100J))/(30kg))\\v=\sqrt(6.67(m^2)/(s^2))\\v=2.58(m)/(s)`

`2.58(m)/(s)` translates to approximately 5.77 mph. Which seems reasonable enough for a child.