Question

If a block of mass 2 kg is pulled up on a smooth inclined of angle 300 with horizontal and the block moves with an acceleration of 1 ms /2 ,then a) find the power delivered by the pulling force at a time 4 second after motion starts . b) what is the average power delivered delivered during this four seconds after the motion starts​

Answer 1

Since the block is moving with acceleration1m/s^2, from FBD we have

F-mgsin\theta=ma

\implies F=m(a+gsin\theta)=20(1+10sin30^{\circ})=120N

Due to acceleration of1m/s^2, after 4 seconds, the body will attain velocity ofv=at=4m/s

Hence the power delivered byFis\vec{F}.\vec{v}=Fv=120N\times 4m/s=480W