Question

A car starting from rest accelerates uniformly to acquire a speed $20km{h}^{-1}$ in 30 min. The distance travelled by car in this time interval will be

• A. 600 km
• B. 5 km
• C. 6 km
• D. 10 km

Answer 1

Answer: (B)

5 km

Here, $u=0,v=20km/h,t=30min=0.5h$
Putting these values in $v=u+at$
$20=0+a\ast 0.5$
We get, $a=40km/h^2$
Putting the values in $S=ut+\frac{1}{2}a{t}^2$
$S=0\ast 0.5+\frac{1}{2}\ast 40\ast {0.5}^2$
$S=5km$