Conservation of Energy Flashcards

Questions and Answers

The term 'conservation of energy' means that the total amount of energy in a system isolated from the rest of the universe remains constant.

True

Efficiency is a measure of the ratio of work done to work available.

True

At what point in its swing is kinetic energy a maximum?

A (correct)

At what point in its swing is potential energy a maximum?

A Signup and view all the answers

Where is the value of kinetic energy equal to zero?

A Signup and view all the answers

Where is potential energy equal to zero?

E Signup and view all the answers

If potential energy at point A is 12 joules, what is the potential energy at B?

9 Signup and view all the answers

If potential energy at point A is 12 joules, what is the potential energy at C?

6 Signup and view all the answers

If potential energy at point A is 12 joules, what is the potential energy at D?

3 Signup and view all the answers

If potential energy at point A is 12 joules, what is the potential energy at E?

0 Signup and view all the answers

Using the law of conservation of energy, what is the kinetic energy at B?

3 Signup and view all the answers

Using the law of conservation of energy, what is the kinetic energy at C?

6 Signup and view all the answers

Using the law of conservation of energy, what is the kinetic energy at D?

9 Signup and view all the answers

Using the law of conservation of energy, what is the kinetic energy at E?

12 Signup and view all the answers

Using the law of conservation of energy, what is the kinetic energy at A?

0 Signup and view all the answers

Choose the correct general statement concerning the total potential and kinetic energy at any point along the arc of the swing.

The total energy at any point along the arc of swing of the pendulum is always equal to 12 Joules Signup and view all the answers

As the pendulum swings from point A to Point E, what will happen to the values for potential and kinetic energy?

Kinetic energy will increase from 0 J to 12 J and the potential energy will decrease from 12 J to 0 J Signup and view all the answers

Calculate the potential energy of the rock before it is released.

3.1 x 10^4 J Signup and view all the answers

What is its kinetic energy before it is released?

0 J Signup and view all the answers

Calculate the approximate speed with which the rock hits the ground.

79 m/s Signup and view all the answers

Was the mass of the object needed to calculate the approximate speed with which the rock hits the ground?

No, because g = 9.8 m/s^2 regardless of mass Signup and view all the answers

Why do all objects hit with the same velocity (ignoring air resistance) if dropped from the same height?

Acceleration due to gravity affects all bodies the same since it depends primarily on the gravity of the planet, not on the object being dropped. Signup and view all the answers

Study Notes

Conservation of Energy Overview

Conservation of energy states that the total energy in an isolated system remains constant, though it may change forms (e.g., potential to kinetic energy).
Efficiency quantifies the ratio of useful work output to the total work input, expressing how much of the energy is effectively utilized.

Kinetic and Potential Energy Distribution

Kinetic energy is highest at point E during the swing of a pendulum.
Potential energy peaks at point A, where it is at its maximum.
Kinetic energy is zero at point A and potentially at other points depending on the height.

Potential Energy Calculations

When potential energy at point A is 12 joules:
- At point B, potential energy is 9 joules.
- At point C, potential energy is 6 joules.
- At point D, potential energy is 3 joules.
- At point E, potential energy is 0 joules.

Kinetic Energy Calculations

Using the conservation of energy principle:
- Kinetic energy at point B is 3 joules.
- Kinetic energy at point C is 6 joules.
- Kinetic energy at point D is 9 joules.
- Kinetic energy at point E is 12 joules.
- Kinetic energy at point A is 0 joules.

Total Energy in the System

The total potential and kinetic energy at any point along the pendulum swing remains constant at 12 joules, affirming the conservation of total mechanical energy.

Energy Transformation During Pendulum Swing

As the pendulum moves from point A to E:
- Kinetic energy increases from 0 joules at point A to 12 joules at point E.
- Potential energy decreases from 12 joules at point A to 0 joules at point E.

Potential Energy of a Falling Object

For an object, such as a rock, potential energy can be calculated using the formula PE = mgh (mass × gravitational acceleration × height).
An example calculation yields a potential energy of 3.1 x 10^4 joules before release.

Kinetic Energy Just Before Impact

Kinetic energy of the rock just before hitting the ground is 0 joules at release, as it is not in motion prior to being dropped.

Speed Calculation on Impact

The speed of the rock upon impact is approximately 79 meters per second, calculated based on conservation laws and gravitational effects.

Mass Independence in Falling Objects

The acceleration due to gravity affects all objects equally, meaning the mass does not influence the speed of descent in a vacuum, allowing different weights dropped from the same height to strike the ground simultaneously at the same speed.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Test your knowledge about the principles of conservation of energy with these flashcards. Explore key concepts such as energy transformation and efficiency, and determine your understanding of the topic with true or false statements.