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Questions and Answers
What defines work done by a force on an object?
What is the SI unit of work?
Which of the following describes positive work?
What is the relationship between work and kinetic energy?
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What happens to the work done if the force is exerted at an angle to the displacement?
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Which of these statements is true regarding the work done against gravity?
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Which of the following equations represents work done by a constant force?
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What characterizes negative work?
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What is true when the force is perpendicular to the displacement of an object?
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What happens to the kinetic energy of a particle when it is at rest?
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How does kinetic energy change with the speed of an object?
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According to the work-energy theorem, what does the work done by the net force on a particle equal?
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What is true about the work done by external forces acting on the skater?
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What effect does total work have on a particle's speed?
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What is the relationship between mass and kinetic energy?
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When does a weightlifter do no work on a barbell?
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What does the work done by a varying force from position $x_1$ to $x_2$ depend on?
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How is the work done on a spring to stretch it a distance $X$ expressed mathematically?
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What is the SI unit of power?
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Which of the following formulas represents average power?
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What is the relationship between force and the distance a spring is stretched?
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In the context of motion along a curve, how is work found?
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What is instantaneous power?
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If a force varies with position, what is the first step to calculate the total work done?
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Study Notes
Work
- Work done by a force involves a displacement of the object the force is acting on.
- Unit of work is the Joule (J) which is defined as 1 Newton (N) of force multiplied by 1 meter (m) of distance.
- Positive work occurs when the force component is in the direction of displacement.
- Negative work occurs when the force component acts opposite to the direction of displacement.
- Zero work occurs when the force is perpendicular to the displacement.
Kinetic Energy
- The energy of motion of an object is referred to as kinetic energy.
- The amount of kinetic energy is dependent on mass and speed, not direction.
- Kinetic energy can never be negative and is only zero when the object is at rest.
- The SI unit of kinetic energy is the Joule.
Work-Energy Theorem
- The work done by the net force on a particle is equal to the change in the particle's kinetic energy.
Power
- Power is the rate at which work is done.
- Average power is calculated by dividing the work done by the time taken.
- Instantaneous power is calculated by taking the derivative of work with respect to time.
- The SI unit of power is the Watt (W), which is equivalent to 1 Joule (J) per second (s).
- Another unit of power is the horsepower (hp) which is equivalent to 746 Watts (W).
Work Done by a Varying Force
- When the force is not constant, the work done can be calculated by integrating the force over the displacement.
- The total work done by the force over a distance is represented by the area under the curve of force versus position.
Work - Energy Theorem for Curved Path
- The work done by a force along a curved path is represented by a line integral of the force along the path.
Stretching a Spring
- The force required to stretch a spring is proportional to the distance it is stretched.
- The work done to stretch a spring is equal to 1/2 times the spring constant (k) multiplied by the square of the distance stretched.
Examples
- When a force is applied to an object at an angle to the direction of motion, only the component of the force parallel to the motion will do work.
- The work-energy theorem can be used to calculate the speed of an object after a certain amount of work has been done on it.
- The power output of a motor can be calculated by dividing the work done by the time taken.
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Description
Dive into the fascinating concepts of work, kinetic energy, and power in physics. This quiz covers the essentials of how work is defined, the work-energy theorem, and the relationship between force and energy. Test your understanding of these fundamental principles!
