The figure shows a 0.3 kg baseball just before and just after it collides with a
ID: 3163252 • Letter: T
Question
The figure shows a 0.3 kg baseball just before and just after it collides with a bat. Just before, the ball has velocity v_1 of magnitude 12.2 m/s and angle theta_1 = 38.6 degree. Just after, it is traveling directly upward with velocity v_2 of magnitude 10.0 m/s. The duration of the collision is 1.40 ms. What are the (a) magnitude and (b) direction (relative to the positive direction of the x axis) of the impulse on the ball from the bat? What are the (c) magnitude and (d) direction of the average force on the ball from the bat? (a) Number Units (b) Number Units (c) Number Units (d) Number UnitsExplanation / Answer
a) Impulse equals change in momentum.
component of velocity before hitting <-9.5, -7.6> [using trig to resolve the velocity vector...and assuming the ball is going DOWNWARD at an angle of 38.6 degrees...pitchers do not pitch upward..this also assumes that the ball is coming from the left to the right, hence the negative in front of the x component as well.]
Afterward, the ball has a velocity of <0,10>.
Change in velocity = <9.5,17.6>
Change in momentum = mass * |Change in velocity| = 0.3*20.00 = 6.00 kgm/s
b) Direction is the same as direction of change in velocity <10.4,17.3>. The direction is then Atan(17.6/9.5) = 61.64 degrees.
c)Average force equals impulse divided by time: 6.00/1.4 = 4.29N
d) Direction of force is the same as direction of impulse.