Answer to Question #257748 in Mechanics | Relativity for Samwise

Question

A car reaches a velocity of 20m/s with an acceleration of 2m/s

2

. How far will it travel while it is 

accelerating if it (a) Initially at rest? (b). initially moving at 10m/s

Answer 1

Explanations & Calculations

• The equation to be employed is $\small v^2=u^2+2as$ as you are given the final velocity, the constant acceleration and the initial velocity in each case.

a)

• Initially at rest ($\small u = 0\,ms^{-1}$)

$\qquad\qquad \begin{aligned} \small (20\,ms^{-1})^2&=\small (0\,ms^{-1})^2+2\times2\,ms^{-2}\times S_1\\ \small S_1&=\small \bold{100\,m} \end{aligned}$

b)

• Initially moving ($\small u= 10\,ms^{-1}$)

$\qquad\qquad \begin{aligned} \small (20\,ms^{-1})^2&=\small (10\,ms^{-1})^2+2\times2\,ms^{-2}\times S_2\\ \small S_2&=\small \bold{75\,ms^{-1}} \end{aligned}$