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Questions and Answers
What occurs when an object with energy exerts a force on another object?
What occurs when an object with energy exerts a force on another object?
What is the SI unit of energy?
What is the SI unit of energy?
What happens when a balloon is pressed gently?
What happens when a balloon is pressed gently?
Which form of energy is associated with an object's movement?
Which form of energy is associated with an object's movement?
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What is mechanical energy a sum of?
What is mechanical energy a sum of?
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When a raised hammer falls on a nail, what is the result?
When a raised hammer falls on a nail, what is the result?
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Which of the following is NOT a form of energy mentioned?
Which of the following is NOT a form of energy mentioned?
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What happens to the balloon when it receives enough energy from hard pressing?
What happens to the balloon when it receives enough energy from hard pressing?
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Why is the work done by a centripetal force always zero?
Why is the work done by a centripetal force always zero?
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What formula represents the work done by an applied force against gravity while lifting an object?
What formula represents the work done by an applied force against gravity while lifting an object?
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How much work is done when a woman walks with a suitcase at constant velocity?
How much work is done when a woman walks with a suitcase at constant velocity?
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What is the work done when a force of 5 N displaces an object through 2 m in the same direction?
What is the work done when a force of 5 N displaces an object through 2 m in the same direction?
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Calculate the work done by a porter lifting 15 kg luggage to a height of 1.5 m, given g = 10 m/s².
Calculate the work done by a porter lifting 15 kg luggage to a height of 1.5 m, given g = 10 m/s².
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What type of energy does the light from the Sun provide to support life on Earth?
What type of energy does the light from the Sun provide to support life on Earth?
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What kind of work is done when the angle between force and displacement is obtuse (90° < θ < 180°)?
What kind of work is done when the angle between force and displacement is obtuse (90° < θ < 180°)?
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How much work is done when a vacuum cleaner is pulled 3.0 m by a force of 50.0 N at an angle of 30.0° with the horizontal?
How much work is done when a vacuum cleaner is pulled 3.0 m by a force of 50.0 N at an angle of 30.0° with the horizontal?
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When a fast-moving cricket ball hits a stationary wicket, what type of energy transformation occurs?
When a fast-moving cricket ball hits a stationary wicket, what type of energy transformation occurs?
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What is a simple definition of energy?
What is a simple definition of energy?
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Which force is doing positive work when lifting an object against gravity?
Which force is doing positive work when lifting an object against gravity?
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What is the work done by centripetal force on a satellite moving in a circular path?
What is the work done by centripetal force on a satellite moving in a circular path?
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What must be equal in order for work to be done on an object against gravity?
What must be equal in order for work to be done on an object against gravity?
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When the angle between the displacement and the force is zero degrees, what is the nature of the work done?
When the angle between the displacement and the force is zero degrees, what is the nature of the work done?
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In the scenario where the displacement is directly opposite to the force applied, what is the work done?
In the scenario where the displacement is directly opposite to the force applied, what is the work done?
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If the work done is calculated with an obtuse angle between force and displacement, what is the value of cos(θ)?
If the work done is calculated with an obtuse angle between force and displacement, what is the value of cos(θ)?
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What is the relationship between kinetic energy and speed of an object?
What is the relationship between kinetic energy and speed of an object?
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From the Work-Energy Theorem, what does the work done on an object represent?
From the Work-Energy Theorem, what does the work done on an object represent?
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What is the kinetic energy of an object with a mass of 15 kg moving at a velocity of 4 m/s?
What is the kinetic energy of an object with a mass of 15 kg moving at a velocity of 4 m/s?
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If the mass of an object is doubled, what happens to its kinetic energy?
If the mass of an object is doubled, what happens to its kinetic energy?
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How much work is required to increase the velocity of a car from 30 km/h to 60 km/h if its mass is 1500 kg?
How much work is required to increase the velocity of a car from 30 km/h to 60 km/h if its mass is 1500 kg?
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What is the potential energy of a 10 kg object at a height of 6 m above the ground? (g = 9.8 m/s²)
What is the potential energy of a 10 kg object at a height of 6 m above the ground? (g = 9.8 m/s²)
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In the formula W = (mv² - mu²)/2, what does W represent?
In the formula W = (mv² - mu²)/2, what does W represent?
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If an object's speed is doubled, what happens to its kinetic energy?
If an object's speed is doubled, what happens to its kinetic energy?
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What is the gravitational potential energy of a 12 kg object at a height of 4 m above the ground, given that g = 10 m s^-2?
What is the gravitational potential energy of a 12 kg object at a height of 4 m above the ground, given that g = 10 m s^-2?
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If the table is considered the zero level for gravitational potential energy, what would be the potential energy of an egg resting on the table?
If the table is considered the zero level for gravitational potential energy, what would be the potential energy of an egg resting on the table?
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What type of potential energy is described when a spring is compressed or stretched?
What type of potential energy is described when a spring is compressed or stretched?
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As a volleyball falls from the second-floor roof to the first-floor roof, what happens to its gravitational potential energy as it reaches the first-floor roof?
As a volleyball falls from the second-floor roof to the first-floor roof, what happens to its gravitational potential energy as it reaches the first-floor roof?
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If an external force does not act on a spring, what is the state of the spring's potential energy?
If an external force does not act on a spring, what is the state of the spring's potential energy?
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What determines the amount of elastic potential energy stored in a spring?
What determines the amount of elastic potential energy stored in a spring?
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When a slow-moving elephant is compared to a fast-moving fox, what could be true about their respective kinetic energies?
When a slow-moving elephant is compared to a fast-moving fox, what could be true about their respective kinetic energies?
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What happens to the gravitational potential energy of an object as it descends from a height?
What happens to the gravitational potential energy of an object as it descends from a height?
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Study Notes
Work Done
- Work done is the product of force and displacement in the direction of the force.
- When the angle between force and displacement is 0 degrees (same direction), the work done is positive.
- When the angle between force and displacement is 180 degrees (opposite direction), the work done is negative.
- When the angle between force and displacement is obtuse (90° < θ < 180°), the work done is negative.
Examples of Work Done
- A force of 5N acting on an object displacing it 2 meters in the direction of the force results in 10J of work.
- Work done by a 50N force pulling a vacuum cleaner 3 meters at a 30-degree angle with the horizontal: 129.75 J.
Forces and Work
- Lifting an object upwards results in positive work done by the applied force.
- Gravity does negative work when an object is lifted because it acts against the direction of displacement.
- Centripetal force does zero work because it is always perpendicular to the displacement of an object moving in a circular path.
Work Done Against Gravity
- Work done against gravity to lift an object to a height (h) is calculated as: W = mgh
- m = mass of object
- g = acceleration due to gravity
- h = height
Energy
- Energy is the capacity to do work.
- Examples of objects possessing energy:
- Car engine using energy from burning petrol
- Moving cricket ball hitting a wicket
- An object placed at a certain height
- Hammer driving a nail
- Compressed balloon
- Energy is measured in joules (J).
- 1kJ (kilo joule) = 1000 J
Mechanical Energy
- Energy associated with the movement or position of an object.
- Two types:
- Kinetic energy
- Potential energy
Kinetic Energy
- Energy possessed by an object due to its motion.
- Work done on an object increases its kinetic energy.
- Calculated using the formula: Ek = 1/2mv²
- m = mass of object
- v = velocity of object
- Doubling the speed of an object quadruples its kinetic energy.
- Doubling the mass of an object doubles its kinetic energy.
Gravitational Potential Energy
- Energy possessed by an object due to its position relative to a reference point (usually ground level).
- Calculated using the formula: Ep = mgh
- m = mass of object
- g = acceleration due to gravity
- h = height relative to the reference point
- The reference point for calculating potential energy can be chosen arbitrarily.
Elastic Potential Energy
- Energy stored in an object due to its deformation, such as compression or stretching.
- Common examples:
- Compressed springs
- Stretched strings
- The amount of elastic potential energy stored depends on the amount of deformation from the object's relaxed length.
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Description
Explore the concept of work done in physics, understanding how force and displacement influence work. This quiz covers key principles, including the effects of angles on work done and examples illustrating these concepts. Test your knowledge on how different forces work in various scenarios!
