Question

An object is 5kg and acceleration 30ms-1. After going 100 m the object starts to go at an acceleration of 30 ms-1. If after 100m we stop the force on object. How long will it go for?. Friction 10N.

Answer 1

$$v=at\\v=\frac{F_f}{m}t\\30=\frac{10}{5}t\\t=15\ s$$