During a neighborhood baseball game in a vacant lot, a particularly wild hit sen
ID: 2192147 • Letter: D
Question
During a neighborhood baseball game in a vacant lot, a particularly wild hit sends a 145-g baseball crashing through the pane of a second-floor window in a nearby building. The ball strikes the glass at 11.7 m/s, shatters the glass as it passes through, and leaves the window at 8.15 m/s with no change of direction. Calculate the magnitude of this impulse (a positive number). The ball is in contact with the glass for 10.1 ms as it passes through. Find the magnitude of the average force of the glass on the ball (a positive number).Explanation / Answer
Since there is no change in direction, the impulse must be in exactly the opposite direction to the velocity (direction of travel) of the baseball.
Impulse = change in momentum = (8.15 - 11.7)m/s * 0.145kg = -0.515 N.s
(negative sign indicates opposite direction to velocity)
Magnitude of impulse =0.515 N.s (or 0.515 kg.m/s)
Impulse = F.dt
so average force F = 0.515 N.s / 10.1*10^-3 s = 50.97 N