Frictional Force Honors

Suppose you have a 120-kg wooden crate resting on a wood floor (μs = 0.5, μk = 0.3). You push the crate to the right.

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Draw a free body diagram for the crate.

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What maximum force can you exert horizontally on the crate without moving it?

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If you continue to exert this force once the crate starts to slip, what will its acceleration then be?

An 81-kg baseball player slides into second base. The coefficient of kinetic friction between the player and the ground is 0.49.

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Draw a free body diagram of the baseball player

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What is the magnitude of the frictional force?

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If the player comes to rest after 1.6 s, what was his initial velocity?

A cup of hot chocolate is sitting on the dashboard of a car that is traveling at a constant velocity. The coefficient of static friction between the cup and the dashboard is 0.30. Suddenly, the car accelerates.

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Draw the free body diagram of the coffee cup

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What is the maximum acceleration that the car can have without the cup sliding backward off the dashboard?

A 20.0-kg sled is being pulled across a horizontal surface at a constant velocity. The pulling force has a magnitude of 80.0 N and is directed at an angle of 30.0° above the horizontal.

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Draw a free body diagram for the sled.

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Determine the coefficient of kinetic friction.

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If the sled is being pulled at 1.0 m/s and the person stops pulling, how far will it slide before it stops.

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If a taller person pulls the sled so that the pulling force is directed at an angle of 45.0° above the horizontal, what magnitude of force would be necessary to maintain constant velocity?

A skier is heading down a 10.0° slope. The coefficient of friction for waxed wood on wet snow (𝜇𝑘 = 0.1). 

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Draw a free body diagram for the skier

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Calculate the acceleration of a skier.

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Suppose you have a 120-kg wooden crate resting on a wood floor (μs = 0.5, μk = 0.3). You push the crate to the right.

Draw a free body diagram for the crate.

What maximum force can you exert horizontally on the crate without moving it?

If you continue to exert this force once the crate starts to slip, what will its acceleration then be?

An 81-kg baseball player slides into second base. The coefficient of kinetic friction between the player and the ground is 0.49.

Draw a free body diagram of the baseball player

What is the magnitude of the frictional force?

If the player comes to rest after 1.6 s, what was his initial velocity?

A cup of hot chocolate is sitting on the dashboard of a car that is traveling at a constant velocity. The coefficient of static friction between the cup and the dashboard is 0.30. Suddenly, the car accelerates.

Draw the free body diagram of the coffee cup

What is the maximum acceleration that the car can have without the cup sliding backward off the dashboard?

A 20.0-kg sled is being pulled across a horizontal surface at a constant velocity. The pulling force has a magnitude of 80.0 N and is directed at an angle of 30.0° above the horizontal.

Draw a free body diagram for the sled.

Determine the coefficient of kinetic friction.

If the sled is being pulled at 1.0 m/s and the person stops pulling, how far will it slide before it stops.

If a taller person pulls the sled so that the pulling force is directed at an angle of 45.0° above the horizontal, what magnitude of force would be necessary to maintain constant velocity?

A skier is heading down a 10.0° slope. The coefficient of friction for waxed wood on wet snow (𝜇𝑘 = 0.1).

Draw a free body diagram for the skier

Calculate the acceleration of a skier.

Find the angle of the slope down which this skier could coast at a constant velocity.