Question

The mass of cyclist together with bike is 90kg. Calculate the increase in kinetic energy if the speed increases from 6km/hr to 12km/hr.

Answer 1

initial speed = 6km/hr = 5/3 m/s
final speed = 12km/hr = 10/3 m/s

∆KE = 1/2 m(v² - u²)
= 1/2 x 90(100/9 - 25/9)
= 375 J

Here ∆KE = Change in kinetic energy
m is mass
v is final velocity
u is initial velocity