Motion Question (1 Viewer)

[mtsmahia]

A trolley, of mass 3kg, moving at 8m/s, is acted on by a force of 15N until its speed doubles. What acceleration does the force produce, and how long does it act?

Thanks!!

 

[n_otesguy]

Use F=ma to work out the acceleration:
15=3a -> a=5 ms^-2

We know that the "final" speed doubles, and the initial speed is 8m/s, so using one of the equations of kinematics we have:
v=u+at
16=8+5t
t=8/5 s.