Question

I'm new to brainy, but here is my question.

Andre, whose mass is 77.1 kg, sits on a diving board above a dunk tank. If he is sitting 0.90 m above the water, what is his total mechanical energy?

Answer 1

680 is the right answer

Answer 2

Answer: 680 J

Step-by-step explanation:

Andre's mechanical energy is given by:

`E=K+U`

where

K is the kinetic energy

U is the gravitational potential energy

The kinetic energy in this case is zero, because Andre is sitting, so its speed is zero: v=0, and the kinetic energy is

`K=(1)/(2)mv^2=(1)/(2)(77.1 kg)(0)^2=0`

The gravitational potential energy is instead

`U=mgh=(77.1 kg)(9.8 m/s^2)(0.90 m)=680.0 J`

So, the total mechanical energy is

`E=U=680.0 J`