Question

What work is said to be done to increase the velocity of a car from $15km/h$ to $30km/h$, if the mass of the car is $1000kg$?

Answer 1

Given:-

$u=15km/h=15\times \frac{5}{18}=\frac{25}{6}m/s$

$v=30km/h=\frac{50}{6}m/s$

Mass = 1000 kg

W=?

$W=△K.E.=\frac{1}{2}m(v^2-u^2)$

$=\frac{1}{2}\times 1000\times \left(\right(50/6{)}^2-\left(25/6{)}^2\right)$

$=\frac{1}{2}\times 1000(900-225)/\left(36\right)$

$=\frac{1}{2}\times 1000\left(675/36\right)$

$K.E.=37500J$

$\therefore$ Work done =37500 Joule.