Question

A car and driver, with a total mass of 1350kg, moving at 30m/s on a horizontal road when the driver sees roadworks ahead. She brakes, decelerating with a constant force of 600N until arriving at the roadworks. Find the time elapsed before arriving at the roadworks.

Answer 1

$\vec F = m \vec a$

$\vec a =\frac{\vec F} {m} = \frac{600} {1350}\approx 0.44$

$\text{the car slows down consequently}$

$v_1 = v_0 -at$

$v_1 = 0$

$t = \frac{v_0}{a}= \frac{30}{0.44}\approx68.18 s$

$\text{Answer: } 68.18 s$