Normal and Frictional Force

A 35-kg crate rests on a horizontal floor, and a 65-kg person is standing on the crate.

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Draw the Free Body Diagram for the person

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Draw the Free Body Diagram for the crate

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Determine the magnitude of the normal force that the floor exerts on the crate.

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Determine the magnitude of the normal force that the crate exerts on the person.

A 50-kg woman is riding on an elevator. 

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Draw the free body diagram for the woman.

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What is her apparent weight when it is accelerating upward at 1.5 m/s2?

A 0.05-kg cookie is on a non-stick (frictionless) cookie sheet inclined at 30°

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Draw the free body digram for the cookie

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What is the acceleration of the cookie as it slides down the cookie sheet?

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If the cookie sheet is 0.75 m long, how much time to you have to catch the cookie before it falls off the edge?

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.

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?

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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A 35-kg crate rests on a horizontal floor, and a 65-kg person is standing on the crate.

Draw the Free Body Diagram for the person

Draw the Free Body Diagram for the crate

Determine the magnitude of the normal force that the floor exerts on the crate.

Determine the magnitude of the normal force that the crate exerts on the person.

A 50-kg woman is riding on an elevator.

Draw the free body diagram for the woman.

What is her apparent weight when it is accelerating upward at 1.5 m/s2?

A 0.05-kg cookie is on a non-stick (frictionless) cookie sheet inclined at 30°

Draw the free body digram for the cookie

What is the acceleration of the cookie as it slides down the cookie sheet?

If the cookie sheet is 0.75 m long, how much time to you have to catch the cookie before it falls off the edge?

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.

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?

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.