Question

You are driving your car at a speed of 19.0 m/s and you hit the brakes. The car accelerates at -3.50 m/s2. (a) How long does it take the car to cover 10.0 m? (b) What is the final velocity of the car?

Answer 1

Recall the formulas,

`x_f=x_i+v_it+\frac12at^2`

`v_f=v_i+at`

(a)

`10.0\,\mathrm m=\left(19.0(\rm m)/(\rm s)\right)+\frac12\left(-3.50(\rm m)/(\mathrm s^2)\right)t^2`

`\implies \boxed{t\approx0.555\,\mathrm s}`

(b)

`v_f=19.0(\rm m)/(\rm s)+\left(-3.50(\rm m)/(\mathrm s^2)\right)(0.555\,\mathrm s)`

`\implies \boxed{v_f\approx17.1(\rm m)/(\rm s)}`