Question

A motorcycle accelerates from a stop at a rate of 4m/s 2 for 20 seconds. It then continues at a

Answer 1

After 20 s, the motorcycle attains a speed of

$\left(4\dfrac{\rm m}{\mathrm s^2}\right)(20\,\mathrm s)=80\dfrac{\rm m}{\rm s}$

and it continues at this speed for the next 40 s. So at 45 s, its speed is 80 m/s.