The loaded \(150-\mathrm{kg}\) skip is rolling down the incline at \(4 \mathrm{~m} / \mathrm{s}\) when a force \(P\) is applied to the cable as shown at time \(t=0\). The force \(P\) is increased uniformly with the time until it reaches \(600 \mathrm{~N}\) at \(t=4 \mathrm{~s}\), after which time it remains constant at this value. Calculate

(a) the time \(t^{\prime}\) at which the skip reverses its direction and \((b)\) the velocity \(v\) of the skip at \(t=8 \mathrm{~s}\). Treat the skip as a particle.

v = 4 m/s P, N 600 30 At t, s 4 ' 8 P