Question

Justin, with a mass of 30 kg, is going down an 8.0-m-high waterslide. He starts at rest, and his speed at the bottom is 11 m/s. Howmuch thermal energy is created by friction during his descent?

Answer 1

Given:

• Mass, m = 30 kg

,

• Height, h = 8.0 m

,

• Initial velocity = 0

,

• Final velocity = 11 m/s

Let's determine how much thermal energy is created by friction during his descent.

Apply the conservation of energy:

`mgh=(1)/(2)mv^2+wf`

Where:

m is the mass = 30 kg

g is acceleration due to gravity = 9.8 m/s²

v is the final velocity = 11 m/s

h is the height = 8.0 m

wf is the thermal energy created by friction.

Let's solve for wf:

`\begin{gathered} wf=mgh-(1)/(2)mv^2 \\ \\ wf=(30*9.8*8.0)-((1)/(2)*30*11^2) \\ \\ wf=2352-1815 \\ \\ wf=537\text{ J} \end{gathered}`

Therefore, the thermal energy is 537 J.

ANSWER:

537 J