Question

A constant force acting on a block of mass `5` kg changes `(a)` its speed from `6m//s` to `10 m//s` in travelling a distance `8m` in a straight line, (b) its speed from `2m//s` to `8m//s` in `3s` a straight line. Find the magnitude and the direction of the force.

Answer 1

As the force is constant, acceleration is also constant
(a) `v^(2)=u^(2)+2as`
`(10)^(2)=(6)^(2)+2axx8rArra=4m//s^(2)`
`F=ma=5xx4=20N`
(b) `v=u+at`
`8=2+axx3rArra=2m//s^(2)`
`F=ma=5xx2=10N`