Question

A cyclist driving at $5m{s}^{-1}$ changes his velocity to $10m{s}^{-1}$ over a distance of $50m$. Calculate the time in which cyclist picks up the above velocity .

• A. $6.67sec$
• B. $4.00sec$
• C. $5.87sec$
• D. $2.45sec$

Answer 1

The correct option is A $6.67sec$

Given:

Initial velocity: $u=5$

Final velocity: $v=10$

Displacement: $s=50$

Using the equation of motion $v^2-u^2=2as$

$a=\frac{v^2-u^2}{2s}=\frac{100-25}{100}$ $\Rightarrow a=0.75$

Now using the equation of motion $v=u+at$

$t=\frac{v-u}{a}$ $\Rightarrow t=\frac{5}{0.75}=6.67sec$

$\therefore t=6.67s$