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What is the impulse delivered to the ball? Answer in units of kg x m/s.A pitcher throws...

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lala25 | Student, Undergraduate | eNotes Newbie

Posted October 27, 2009 at 9:53 PM via web

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What is the impulse delivered to the ball? Answer in units of kg x m/s.

A pitcher throws a 0.15kg baseball so that it crosses home plate horizontally with a speed of 14m/s. It is hit straight back at the pitcher with a final speed of 32m/s.

Given: Choose the positive direction to be from the pitcher to the plate (some answers may be negative).

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krishna-agrawala | College Teacher | Valedictorian

Posted October 27, 2009 at 10:11 PM (Answer #1)

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Mass of Baseball = m = 0.15 kg

Initial velocity of ball = 14 m/s

Final velovity of ball = u = - 32 m/s

Impulse delivered to ball = v = m*(v-u) = 0.15*(-32 -14)

= 0.15*(-46) = - 6.9 kg x m/s

Answer: Impulse delivered to the ball is - 6.9 kg x m/s


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neela | High School Teacher | Valedictorian

Posted October 28, 2009 at 1:03 AM (Answer #2)

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The impulse is the change of momentum. Momentum is the product of the mass and the velocity of an object. Or in other words, mass times the velocity is the momentum.

We take the direction of delivery of the ball  to the plate as positive and the opposite as negatve.

The momentum of the ball thrown by the pitcher  while crossing the home plate = mass of the ball * its velocity.= 0.15kg*14m/s.

After the ball is hit its velocity = 32m/s in the opposite direction or -32m/s,

The momentum of the ball after hit = (0.15kg)*(-32m/s).

Therefore the change of momentum = final momentum - initial momentum before hit = (-0.15kg)*(32m/s)-(0.15 kg)*(14m/s)

= - 6.9 kg m/s is the impulse or the change of momentum in the  ball after hit.


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