CP A 2.8-kg block slides over the smooth, icy hill shown in Fig. P7.46. The top of the hill is horizontal and 70 m higher than its base. What minimum speed must the block have at the base of the 70-m hill to pass over the pit at the far (right-hand) side of that hill?

Solution 50P Step 1: Data given Mass m = 2.8 kg Height h = 70.0 m We know by work energy relation PE = KE We have PE = mgh and KE = 1/2 mv 2 Relating these two values we get mgh = 1/2 mv 2 Rearranging to find v 2gh = v 2 Substituting values we get v = 2 × 9.8 m/s × 70.0 m v = 1372 m /s2 2 v = 37.0 m/s Hence we get initial velocity to attain height 70 m as 37.0 m/s