Two baseballs are consecutively hit by a bat. The first ball is hit 20cm from th
ID: 1528279 • Letter: T
Question
Two baseballs are consecutively hit by a bat. The first ball is hit 20cm from the bats axis of rotation and the second ball is hit 40cm from the bat's is of rotation. If the angular velocity of the bat was 30 rad/s at the instant that both balls were contacted, what was the linear velocity of the bat the two contact points? A polo players arm and stick form a 2.5 m rigid segment. If the arm and stick are swung with an angular speed of 1.0 rad/s as the player's horse gallops at 5m/s, what is the resultant velocity of the motionless ball that is struck head-on? (Assume that ball velocity is the same as the linear velocity of the end of the stick). During an elbow flexion exercise, the relative angle at the elbow was 10 degrees at 0.5s and 120 degrees at 071s. That was the angular velocity of the elbow?Explanation / Answer
2. linear velocity, v = w r
v1 = 30 x 0.20 = 6 m/s .... first ball
for second ball: v2 = 30 x 0.30 = 12 m/s
3. linear velocity wrt horse = 1 x 2.5 = 2.5 m/s
w r t to gorund = 2.5 + 5 = 7.5 m/s
4. angular velocity = delta(theta) / time
= (120 - 10) / (0.71 - 0.5)
= 523.8 deg /s
Or 9.14 rad/s