Work And Power
Overview
Lifting a suitcase, kicking a ball, climbing a hill: every one of these actions involves a force moving through a distance, and every one transfers energy from one store to another. The physics behind them centres on three tightly connected quantities: work, energy and power.
In this lesson you will learn how to calculate work done by a force, gravitational potential energy for an object at height, and kinetic energy for a moving object. You will see how conservation of energy links these stores together, and finish with power, the rate at which energy is transferred. These equations appear on almost every Edexcel Paper 1 sitting.
Objectives
- Know and use the relationship between work done, force and distance moved in the direction of the force: work done = force x distance moved, W = F x d
- Know that work done is equal to energy transferred
- Know and use the relationship between gravitational potential energy, mass, gravitational field strength and height: GPE = m x g x h
- Know and use the relationship: kinetic energy = 1/2 x mass x speed2, KE = 1/2 x m x v2
- Understand how conservation of energy produces a link between gravitational potential energy, kinetic energy and work
- Describe power as the rate of transfer of energy or the rate of doing work
- Use the relationship between power, work done (energy transferred) and time taken: power = work done / time taken, P = W / t
Lesson Note
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Lesson Evaluation
Congratulations on completing the lesson on Work And Power. Now that youve explored the key concepts and ideas, its time to put your knowledge to the test. This section offers a variety of practice questions designed to reinforce your understanding and help you gauge your grasp of the material.
You will encounter a mix of question types, including multiple-choice questions, short answer questions, and essay questions. Each question is thoughtfully crafted to assess different aspects of your knowledge and critical thinking skills.
Use this evaluation section as an opportunity to reinforce your understanding of the topic and to identify any areas where you may need additional study. Don't be discouraged by any challenges you encounter; instead, view them as opportunities for growth and improvement.
- A force of 50 N pushes a box 4 m across a floor. How much work is done? A) 12.5 J B) 54 J C) 200 J D) 800 J Answer: C
- A 3 kg object is lifted 5 m above the ground (g = 10 N/kg). What is its gravitational potential energy? A) 15 J B) 50 J C) 150 J D) 300 J Answer: C
- A ball of mass 0.2 kg travels at 10 m/s. What is its kinetic energy? A) 1 J B) 2 J C) 10 J D) 20 J Answer: C
- An object falls freely from rest. As it falls, which statement is correct (ignoring air resistance)? A) Its total energy increases B) Its GPE increases and KE decreases C) Its GPE decreases and KE increases by the same amount D) Its KE stays the same Answer: C
- A motor does 6000 J of work in 30 seconds. What is its power? A) 20 W B) 200 W C) 180 000 W D) 6030 W Answer: B
Available on the Green Bridge App
Download the Green Bridge CBT app on your phone or computer to access full lesson notes, practice questions, and more.
Available on the Green Bridge App
Download the Green Bridge CBT app on your phone or computer to access full lesson notes, practice questions, and more.
Recommended Books
Practice Mock Questions
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