Question

A 60 kg bicyclist going 2 m/s increased his work output by 1,800 J. What was his final velocity?

Answer 1

8 was the correct answer, thanks

Answer 2

Bicyclist initial kinetic energy is Ek=(1/2)*m*v² where m is his mass and v is his speed and that is equal to:

Ek=(1/2)*60*2²=120 J.

When we add the increased work output, we get the total kinetic energy:

Ek(total)=Ek+W= 120 J + 1800 J= 1920 J

So Ek(total)=1920 J = (1/2)*m*V² where V is the speed after the bicyclist increased his work output. So lets solve for V:

(1/2)*60*V²=1920

30*V²=1920, we divide by 30,

V²=64, and take the square root of both sides,

V=8 m/s. 

So the speed of the bicyclist after the increased work output is V=8 m/s.