Question

A car moves with speed $60km/h$ for $1$ hour in east direction and with same speed for $30min$ in south direction. The displacement of car from initial position is:

• A. $60km$
• B. $30\sqrt{3}km$
• C. $30\sqrt{5}km$
• D. $60\sqrt{2}km$

Answer 1

The correct option is C $30\sqrt{5}km$

Given that,

Speed$v=60km/h$

Time

$t_1=1h$

$t_2=30min$

Now, distance travelled by a car in East direction

$D_1=v\times t_1$

$D_1=60\times 1$

$D_1=60km$

Now, distance travelled by a car in south direction

$D_2=v\times t_2$

$D_2=60\times \frac{1}{2}$

$D_2=30km$

Now, the displacement from intial position

$D=\sqrt{{\left(D_1\right)}^2+{\left(D_2\right)}^2}$

$D=\sqrt{{\left(60\right)}^2+{\left(30\right)}^2}$

$D=\sqrt{3600+900}$

$D=\sqrt{4500}$

$D=30\sqrt{5}$

Hence, the displacement of car from initial position is $30\sqrt{5}m$