Physics - W.E.P. Question with Solution | TestHub

The block stays at rest relative to B, whose acceleration is $1m/{\mathrm{s}}^2$

Frame A (ground): in 1 s the block gains $v=at=1m/s$, so $W_{\text{all}}=\Delta K=\frac{1}{2}(1)(1{)}^2=0.5\mathrm{J}$

Frame B: the block is stationary, no displacement and no $\Delta K$: $W_{\text{all}}=0$

Frame C: the block's velocity changes $-1\to 0m/s$: $W_{\text{all}}=\Delta K=0-\frac{1}{2}(1)(1{)}^2=-0.5\mathrm{J}$

Ans. (A,B,C,D)