During a neighbourhood baseball game in a vacant lot, a particularly wild hit se
ID: 1441924 • Letter: D
Question
During a neighbourhood baseball game in a vacant lot, a particularly wild hit sends a 147-g baseball crashing through the pane of a second-floor window in a nearby building. The ball strikes the glass at 10.9 m/s, shatters the glass as it passes through, and leaves the window at 8.21 m/s with no change of direction. What is the direction of the impulse that the glass imparts to the baseball? Calculate the magnitude of this impulse (a positive number). The ball is in contact with the glass for 10.9 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 = (8.21 - 10.9)m/s * 0.147kg = -0.395 N.s
(negative sign indicates opposite direction to velocity)
Magnitude of impulse = 0.395 N.s (or 0.395kg.m/s)
Impulse = F.dt
so average force F = 0.395 N.s / 10.9*10^-3 s = 36.23 N