- #1

Glenboro

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## Homework Statement

After being hit, a 0.145 kg baseball has a speed of 45.6 m/s.

1. What is the kinetic energy of the baseball after it has been hit?

2. How much work is done on the baseball by the baseball bat?

3. In moving through the air, the baseball slows down to a speed of 30.0 m/s. What work has the air done on the ball?

## Homework Equations

K= (1/2)(m)v2

W= KEf-KEo[/B]

## The Attempt at a Solution

1. KE = (1/2)(0.145kg)(45.6m/s)^2

KE = 150.75 J or 1.5 x 10^2J

2. W = 150.75J- 0J = 150.75J ( I assuming KEo is 0J since the kinetic energy of the baseball did not change even though its direction of motion is reversed)[/B]

**3. W= KEf - KEo**

W= (1/2)(0.145kg)(30.0m/s)^2 - 150.75j

W= 65.25 J - 150.75J

W = -85.5 J

I solved these 3 questions, but I don't think this isn't the right answers. Any criticism, advice or hint is appreciated.

W= (1/2)(0.145kg)(30.0m/s)^2 - 150.75j

W= 65.25 J - 150.75J

W = -85.5 J

I solved these 3 questions, but I don't think this isn't the right answers. Any criticism, advice or hint is appreciated.