Question

How much work should be done on a bicycle of mass 20 kg to increase its speed from 2m/s to 5m/s

Answer 1

EXPLANATION

mass of bicycle = 20kg

speed increase from 2m/s to 5m/s

TO FIND WORK DONE.

IN CASE [1]

Mass of bicycle = 20kg

speed of bicycle = 2m/s

so,

formula of kinetic energy

$ke \: = \frac{1}{2}m {v}^{2}$

$\frac{1}{2} \times 20 \times 2 \times 2$

$20 \times 2$

$40 \: joule$

IN CASE [2]

Mass of bicycle = 20kg

speed of bicycle = 5m/s

so,

kinetic energy =

$ke \: = \frac{1}{2} mv {}^{2}$

$\frac{1}{2} \times 20 \times 5 \times 5$

$10 \times 5 \times 5$

$250 \: joule$

WORK DONE = CHANGE IN KINETIC ENERGY

W = ∆KE

W = K2 - K1

W = 250 - 40

W = 210 JOULE

work done = 210 joule