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.
