Question

If your car accelerates from rest at a steady rate of 4.2 m/s^2, how soon will it reach 72 km/h ( 44.7 mph or 20 m/s)?

Answer 1

Answer:

The car will reach 20 m/s in 4.76 seconds

Explanation:

The car moves following an uniformly accelerated motion, therefore we know that $v=v_0+ a(t-t_0)$

Where $v_0 = 0$ are $t_0 =0$

Then $t= \frac{v}{a}=\frac{20 m/s}{4.2 m/s^{2}}=4.76s$