Question

What is her kinetic energy just before she hits the water? Who’s is Julie’s speed just as she hits the water?

Answer 1

a. 2881.2 J

b. 10.8 m/s

Explanation:

Given:

Mass (m) = 49 kg

Height (h) = 6 m

The first thing is to determine the potential energy using the following formula:

`\begin{gathered} E_P=mgh \\ \\ \text{ we replacing:} \\ \\ E_P=(49)(9.8)(6) \\ \\ E_P=2881.2\text{ J} \end{gathered}`

a.

Potential energy is equal to kinetic energy, therefore:

`\begin{gathered} E_K=E_P \\ \\ E_K=2881.2\text{ J} \end{gathered}`

Now we calculate the speed as follows:

`\begin{gathered} E_K=(1)/(2)mv^2 \\ \\ \text{ We replacing:} \\ \\ 2881.2=(1)/(2)(49)v^2 \\ \\ v^2=2\cdot(2881.2)/(49) \\ \\ v=√(117.6) \\ \\ v=10.8\text{ m/s} \end{gathered}`