A tennis ball is hit into the air with a racket. When is the balls kinetic energy the greatest?

Physics

1 answer:

madam [21]3 years ago

3 0

Answer:

Kinetic energy is maximum when the player hits the ball.

Explanation:

Kinetic energy $=\frac{1}{2} mv^2$ , where m is the mass and v is the velocity.

So kinetic energy is proportional to square of velocity.

Velocity is maximum when the player hits the ball.

So kinetic energy is maximum when the player hits the ball.

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A marble of mass m initially at rest at height h moves along a frictionless rail that forms a hoop of radius R. At the end of th

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Answer:

a. The minimum value for h is 2R.

b. The maximum compression of the spring is $\sqrt{\frac{4mgR}{k}}$ .

Explanation:

a. If the marble is initially at rest, then its total mechanical energy is equal to its potential energy at that point, mgh. The rail forms a hoop of radius R. In order for the marble to hit the spring, it must reach the top of the hoop, otherwise it falls down.

The height of top of the hoop is 2R. So, in order for the marble to reach the top of the hoop, the height h must be greater than or equal to height of the hoop, 2R.

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In this case, the minimum value for h is 2R.

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Answer:

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