2.A mass of $2.0\,kg$ is pulled by a variable horizontal force $F$ on a smooth surface. A thread attached to the mass passes over an ideal pulley and supports another mass of $3.0\,kg$.
The variation of $F$ with the distance $d$ moved by the mass of $2.0\,kg$ is shown in the graph.
1.Calculate work done, in $J$, on the $2.0\,kg$ mass by the force $F$ when the mass travelled $0.90m$. $J$
2.Calculate the final speed of the $2.0\,kg$ mass. $m\;s^{-1}$
3.On another occasion, the horizontal force is no longer applied and the $2.0\,kg$ mass is replaced with a motor which pulls the $3.0\,kg$ mass with a constant speed of $0.50\,m\;s^{-1}$.
1.On the graph, show the variation of the change in gravitational potential energy Δ$E_p$ of the mass with time $t$.(no need to add values to the axes)
2.The power supplied to the motor is $20\,W$. Calculate the efficiency of the motor. %
