General Physics 1 - Unit 7: Work, Power, and Energy

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Questions and Answers

What is true about work done when force and displacement are perpendicular?

Work is negative.

Work cannot be determined.

Work is positive.

There is no work done. (correct)

Which scenario illustrates zero work being done?

Holding a glass still. (correct)

Pulling a cart for 5 meters.

Pushing an object in the direction of force.

Lifting a box straight up.

How is work calculated when constant force is applied?

Force plus displacement.

Force divided by distance.

Displacement divided by force.

Force times distance. (correct)

If the applied force is towards the ground and the displacement is upwards, what type of work is done?

Negative work. Signup and view all the answers

What overall conclusion can be drawn if a person pulls a heavy suitcase up a hill?

Positive work is done due to movement against gravity. Signup and view all the answers

Which of the following best defines work in a physics context?

Work is the energy transferred when an object moves. Signup and view all the answers

When the force applied by a person is consistent but the distance varies, what method can determine work done?

Graphical methods. Signup and view all the answers

In which situation is work done considered negative?

When lowering an object downwards. Signup and view all the answers

What is the SI unit of work?

Joule Signup and view all the answers

If a person pushes a chair with a constant force but does not move it, what is the work done on the chair?

Zero work Signup and view all the answers

Which of the following scenarios would result in negative work being done?

Lowering a dumbbell to the ground Signup and view all the answers

How is work calculated when a force is applied at an angle?

Work = Force × Distance × cos(θ) Signup and view all the answers

In the context of physical activity, which situation does NOT involve doing work?

Holding a dumbbell stationary Signup and view all the answers

Which of the following best describes work in physics?

The energy transferred when a force is applied Signup and view all the answers

During which of the following activities is the most work likely to be done?

Pushing a heavy cart for 5 meters Signup and view all the answers

When converting work done in Joules to calories, what is the equivalent value of 1 Joule?

0.239 calories Signup and view all the answers

When is work considered negative?

When the force and displacement are in opposite directions Signup and view all the answers

Which situation is an example of work being done?

Sliding a book across a table Signup and view all the answers

Which of the following defines work in physics?

The transfer of energy when a force is applied to an object causing a displacement Signup and view all the answers

What condition must be met for work to be done on an object?

Movement must occur in the direction of the applied force Signup and view all the answers

Which of the following is true regarding positive work?

It occurs when the force and displacement are in the same direction Signup and view all the answers

If a constant force of 10 N acts on an object, causing it to move 5 meters in the same direction as the force, how much work is done?

50 Joules Signup and view all the answers

Study Notes

General Physics 1 - Unit 7: Work, Power, and Energy - Lesson 7.1

This lesson covers work in physics
The learning objectives include defining scalar product, determining work done by a force acting on a system, and solving real-life problems involving work
A warm-up activity is provided to introduce the topic
The concept of work is explained as the effect of forces causing change in an object's position, such as pushing a door or moving objects up and down
The dot product (scalar product) is reviewed, defined as A • B = AB cos θ, where A and B represent vector magnitudes, and θ is the angle between them
Work is a scalar quantity, having only magnitude and no direction
Work done by a constant force is W = Fd cos θ, where F is the force component along the displacement direction, d is the displacement, and θ is the angle between force and displacement vectors
Calculating work done by a varying force involves plotting force against distance and calculating the area under the curve
The SI unit of work is the joule (J), equivalent to 1 newton-meter (N⋅m)
The direction of force relative to displacement affects work: parallel (positive), opposite (negative), perpendicular (zero)
Examples and try-it problems are included to illustrate calculation methods
Key formulas for dot product and work calculations are provided
A bibliography of physics textbooks is listed.

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Description

This lesson focuses on the concept of work in physics, including scalar products and the work done by forces. Students will learn to calculate work using various equations and understand its application in real-life scenarios. The session also includes a warm-up activity to engage learners in the topic.