The figure shows a 0.3 kg baseball just before and just after it collides with a
ID: 1393542 • 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 11.0 m/s and angle e1 31.8 Just after, it is traveling directly upward with velocity v 2 of magnitude 9.00 m/s. The duration of the collision is 1.20 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?Explanation / Answer
A)
Impulse in x direction, Jx = m*(v2x - v1x)
= 0.3*(0 - (-11*cos(31.8) )
= 2.8 N.s
Impulse in y direction, Jy = m*(v2y - v1y)
= 0.3*(9 - (-11*sin(31.8) )
= 4.44 N.s
so, |J| = sqrt(Jx^2 + Jy^2)
= sqrt(2.8^2 + 4.44^2)
= 5.25 N.s
b) direction, theta = tan^-1(Jy/Jx)
= tan^-1(4.44/2.8)
= 57.7 degrees
c) imaulse, J = F*t
==> F = J/t
= 5.25/(1.2*10^-3)
= 4375 N
d) direction : same 57.7 degrees with +x axis