Unit 3-4 Review

Unit 3-4 Review

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Unit 3: Newton's 1st Law

Unit 3: Free Body Diagrams

NOTE: Use the previous slide to help identify Forces present.

Multiple Choice

Is this object in equilibrium?

• Yes and it's moving right

• Yes and its at rest

• No, it's accelerating right

• No, it's at rest

Multiple Choice

What's happening in this FBD?

• Forward acceleration

• Braking

• at rest

• constant velocity

Multiple Choice

Here are 3 FBD diagrams for an elevator. Consider them to be A, B, C. Which one shows an elevator moving upward but braking?

• A

• B

• C

• none of these

Multiple Choice

Here are 3 FBD diagrams for an elevator. Consider them to be A, B, C. Which one shows an elevator accelerating upward?

• A

• B

• C

• none of these

Multiple Choice

Here are 3 FBD diagrams for an elevator. Consider them to be A, B, C. Which one shows an elevator at rest?

• A

• B

• C

• none of these

Multiple Choice

A 2-kilogram block slides down a 30° incline as shown above with an acceleration of 2 meters per second squared.

Which of the following diagrams best represents the gravitational force W, the frictional force f, and the normal force N that act on the block?

Multiple Choice

Is it possible for the object in the diagram to be moving to the right and have this FBD?

• Yes. It's possible that the x forces were just left off the diagram.

• Yes. It could be moving at a constant velocity.

• No. The FBD shows that the system is in equilibrium.

• No. An FBD shows all F.

Multiple Choice

When the frictionless system shown above is accelerated by an applied force of magnitude F, the tension in the string between the blocks is

• F

• 2/3 F

• 1/2 F

• 1/3 F

Multiple Choice

A forward force of 15 N is counteracted by a backwards frictional force of 6 N. The mass of the object is 2 kg. what is the acceleration?

• it cannot be determined

• 4.5 m/s/s in the direction of the larger force

• 7.5 m/s/s in the direction of the larger force

• 3 m/s/s in the direction of the smaller force.

Multiple Choice

A force of 8 Newton’s is applied to a crate so that it moves at a constant velocity of 1.5 m/s. What is the net force?

• 1.5 N

• 8 N

• 12N

• 0 N

Multiple Choice

Two people are pulling on the ends of a rope. Each person pulls with a force of 100 N. The tension in the rope is

• 0 N

• 50 N

• 100 N

• 200 N

Unit 4: Velocity, Acceleration, and Force Vectors

Multiple Choice

At point P, he car hits an area of ice and loses all frictional force on it tires. Which path does the car follow on the ice?

• A

• B

• C

• D

Multiple Choice

An object moving is moving with uniform speed in a horizontal counterclockwise circle. At the location depicted, the centripetal force stops. Which path will the object follow?

Multiple Choice

An object is moving with uniform speed in a horizontal, counterclockwise circle. At location B, which way does the acceleration vector point?

• Left

• Right

• Up

• Down

Multiple Choice

At the instant shown in the diagram, the car's centripetal acceleration is directed-

• toward E

• toward N

• toward W

• clockwise

Multiple Choice

A curved groove is place on the top of a level table as shown in the diagram. A ball is pushed in the groove at P so that it leaves at Q. Which picture shows how the ball will move when it leaves the groove at Q?

Multiple Choice

A 10kg car travels at a constant speed of 20.0 m/s around a horizontal circular track. Which diagram correctly represent the direction of the car's velocity (v) and the direction of the centripetal force (Fc) acting on the car at a particular moment?

Multiple Choice

What is the direction of the velocity at point B, if the ball is revolving clockwise?

• up
• right
• down
• left

Multiple Choice

Centripetal acceleration always points

• in the direction of the object's motion
• in the opposite direction of the object's motion
• towards the center of the circle
• towards the outside of the circle

Multiple Choice

The diagram below represents a 2.0-kilogram toy car moving at a constant speed of 3.0 meters per second counterclockwise in a circular path with a radius of 2.0 meters. At the instant shown in the diagram, the centripetal force acting on the car is --

• 4.5 N north

• 4.5 N west

• 9.0 N north

• 9.0 N west

Multiple Choice

A car with mass m travels around a curve with velocity v. What do you know about the centripetal force if the radius triples?

• 9.8?
• Force triples
• Force divides by 3
• Force divides by 9

Multiple Choice

A car with mass m travels around a curve with velocity v. What do you know about the centripetal force if the velocity triples?

• Nothing 
• The centripetal force triples
• the centripetal force multiplies by 9
• The centripetal force divides by 3

Multiple Choice

What's the centripetal acceleration of an object traveling 2.3 m/s around a circle of radius 0.3 m?

• 5 m/s²

• 17.63 m/s²

• 10 m/s²

• 8.81 m/s²

Multiple Choice

Calculate the centripetal force required to make a 5 kg ball move 4 m/s in a circle with a radius of 2 m.

• 10 N
• 20 N
• 30 N
• 40  N

Multiple Choice

A car going around a curve - identify the centripetal force:

• friction

• tension

• force normal

• gravitational force

Multiple Choice

A race car completes three laps of a circular track with a radius of 35 m with a speed of 25 m/s. Determine the centripetal acceleration of the car.

• 0.17 m/s²

• 17.9 m/s²

• 24.4 m/s²

• 1.0 m/s²