Work and Energy | Grade 8 Science DepEd MELC-Based Quarter 1 Module 3 Part 1 Work

Summary

This educational video explores the concept of 'work' in various contexts, from employment to physics. It explains that in physics, work is related to energy transfer, occurring when a force causes displacement in the direction of the force. The formula for calculating work (W = force × displacement) is introduced, with the unit of work being the joule, named after James Prescott Joule. The video also illustrates work with everyday examples like pushing a chair and rolling a ball, emphasizing the energy transfer involved in these actions.

Takeaways

• 🔧 The term 'work' has various meanings, including a job or employment, tasks or activities to be accomplished, and an abstract concept in physics related to energy.
• 🏢 When asked where you work, it typically refers to your job or place of employment.
• 📚 In an educational context, 'work' refers to tasks or activities like homework that need to be completed.
• 🔨 In physics, work is associated with energy and involves a change in energy when it is done.
• 🚶‍♂️ Work is done by an object when it loses energy, and work is done on an object when it gains energy.
• 📐 For work to be done on an object, a force must be applied and the object must move in the direction of the force.
• 📏 The formula to calculate work is Work = Force × Displacement, where the unit of work is the joule (newton meter).
• 👨‍🔬 The unit 'joule' is named after the English physicist James Prescott Joule and is also a unit of energy.
• 🛠️ An example calculation of work involves pushing a chair with a force of 500 newtons over a displacement of 7 meters, resulting in 3500 joules of work done.
• 🎳 In the provided bowling game example, work is done on the ball when it is pushed, transferring energy to it, which then moves as kinetic energy.
• 🧠 The script encourages viewers to keep their minds busy and to subscribe for more educational content.

Q & A

What is the general meaning of the word 'work' in everyday language?

In everyday language, 'work' often refers to a job or employment, or to tasks or activities that need to be accomplished, such as homework.

How is 'work' defined in physics?

In physics, 'work' is defined as the process in which energy is transferred to or from an object when a force is applied, causing displacement in the direction of the force.

What must happen for work to be considered as done on an object?

For work to be considered as done on an object, a force must be applied to the object, and the object must move in the direction of the applied force.

What is the formula used to calculate work done by a force?

The formula to calculate work is: Work = Force × Displacement.

What are the units of force and displacement in the work formula?

The unit of force is the newton (N), and the unit of displacement is the meter (m).

What is the unit of work, and who is it named after?

The unit of work is the joule (J), named after the English physicist James Prescott Joule.

How much work is done if a 500 newton force pushes a chair 7 meters?

The work done is 3,500 joules, calculated by multiplying the force (500 newtons) by the displacement (7 meters).

In the example of rolling a ball to hit bottles, is work done on the ball, and why?

Yes, work is done on the ball because the force exerted on it causes the ball to move in the same direction as the force applied.

What is the relationship between force, work, and energy as described in the script?

The force applied to an object does work on the object, and this work results in a transfer of energy to the object, often causing it to move.

What key concept is emphasized about the direction of force and displacement in the context of work?

The key concept emphasized is that for work to be done, the force applied must cause displacement in the same direction as the force.

Outlines

00:00

🔧 Understanding Work in Different Contexts

This paragraph introduces the concept of 'work' in various contexts, from employment and tasks to the abstract idea in physics related to energy. It explains that work involves a force applied to an object that results in movement in the direction of the force, and no work is done if there's no movement or if the movement is in a different direction. The paragraph also introduces the formula for calculating work (Work = Force × Displacement) and the unit of measurement, the joule, named after James Prescott Joule. An example calculation is provided, illustrating how much work is done when pushing a chair with a force of 500 newtons over a distance of 7 meters, which equals 3500 joules.

05:03

🏀 The Role of Work and Energy in Motion

The second paragraph delves into the concept of work in the context of motion and energy. It uses the example of pushing a ball to hit objects, explaining that work is done when the force exerted is in the same direction as the ball's motion, transferring energy to the ball. This energy then becomes the ball's kinetic energy, allowing it to continue moving even after the initial push. The paragraph concludes by emphasizing the importance of understanding that work results in displacement in the direction of the applied force and encourages viewers to stay curious and engaged with the content.

Keywords

💡Work

In the context of the video, 'work' is a multifaceted term. It first refers to employment or a job, as in the question 'where do you work?'. It also denotes tasks or activities that need to be accomplished, such as homework. In physics, 'work' is an abstract concept related to energy transfer, where work done on or by an object results in a change in energy. The script uses the example of pushing a chair to illustrate work done in terms of force applied over a distance.

💡Employment

Employment is the state of having a job or being hired by someone. In the script, it is mentioned in the context of asking someone where they work, which refers to their occupation or place of work. Employment is a fundamental aspect of societal structure and individual livelihood.

💡Homework

Homework refers to tasks or assignments given by teachers to students to be completed outside of class. The script mentions it when discussing the different meanings of 'work', emphasizing the idea of work as an activity that needs to be accomplished.

💡Physics

Physics is a branch of science concerned with the nature and properties of matter and energy. The script introduces the concept of work in physics as an abstract idea related to energy, where work is associated with a change in energy when it is done by or on an object.

💡Energy

Energy, in the context of the video, is the capacity to do work. It is transferred when work is done, either by an object losing energy or gaining it. The script explains that work is accompanied by a change in energy, which is a fundamental principle in physics.

💡Force

Force is described in the script as an influence that can change the motion of an object. It is a necessary component for work to be done, as work occurs when a force causes an object to move in the direction of the force applied.

💡Displacement

Displacement is the change in position of an object. In the script, it is mentioned in the formula for calculating work, where work is equal to force times displacement. Displacement is a vector quantity that indicates the distance and direction of the object's movement.

💡Newton

A Newton is the unit of force in the International System of Units (SI). The script mentions it as the unit for force when calculating work, with the formula work equals force times displacement. One Newton is the force needed to accelerate one kilogram of mass at the rate of one meter per second squared.

💡Joule

The Joule is the unit of work or energy in the SI system. Named after the English physicist James Prescott Joule, it is defined as the work done by a force of one Newton through a distance of one meter. The script uses the Joule to illustrate the unit of work done in pushing a chair.

💡Motion

Motion refers to the change in position of an object with respect to its surroundings over time. The script discusses how force can change the state of motion of an object, whether it is at rest or moving, and how work is done when there is displacement in the direction of the applied force.

💡Activity

Activity, in the script, is used to describe a simple bowling game as an example of work being done. When a ball is pushed and rolls to hit objects, work is done on the ball, transferring energy to it, which then moves with kinetic energy.

Highlights

The word 'work' has multiple meanings and can refer to employment, tasks, or an abstract concept in physics related to energy.

In physics, work is done when there is a change in energy associated with the movement of an object due to a force.

For work to be done, a force must be applied to an object, and the object must move in the direction of the applied force.

No work is done if the force exerted does not result in movement of the object or if the movement is in a different direction from the force.

The formula for calculating work is work equals force times displacement, represented by the symbol W.

The unit of force is the newton, and the unit of displacement is the meter, making the unit of work the newton meter, also known as a joule.

The joule is named after the English physicist James Prescott Joule and is a unit of energy.

One joule is the amount of work done or energy expended when a force of one newton is applied through a distance of one meter.

An example calculation of work done is pushing a chair with a 500 newton force along a seven-meter aisle, resulting in 3500 joules of work.

Work is done on an object when the force applied causes displacement in the same direction as the force.

The video suggests a simple activity to demonstrate work: playing a bowling game with a ball and plastic bottles to understand the concept of work.

When you push a ball, you do work on it by transferring energy, which then becomes the ball's kinetic energy.

The video emphasizes the importance of understanding the concept of work in physics as it relates to energy and force.

The video concludes by summarizing the conditions under which work is done: force applied causing displacement in the same direction.

The video encourages viewers to subscribe to the channel and turn on notifications for more educational content.

Transcripts

[Music]

what comes to mind when you hear the

word

work the word work has many meanings

[Music]

when people ask where do you work they

refer

to a job or employment

when your teacher asks have you done

your homework

they refer to the tasks or activity you

need to accomplish

in physics work is an abstract idea

related to energy

when work is done it is accompanied by a

change in energy

when work is done by an object it loses

energy

and when work is done on an object it

gains energy

by the way if you still haven't watched

our previous lessons

you can pause this video and watch it

first so you can easily understand a

lesson here

in the previous lessons we learned that

force can change the state of motion of

an object

if an object is at rest it can be moved

by

exerting force on it

if an object is moving it can be made to

move faster or stopped by applying force

on it

in order to say that work is done

on an object there must be force applied

to it

and the object moves in the direction

of the force applied

work is done if the object you push

moves a distance in the direction

towards which you are pushing it

no work is done if the force you exert

does not make the object move

[Music]

no work is also done if the object moves

a distance

in a direction that is not in the

direction

of the fourth supply take this man for

example

the force he uses to carry the backpack

is upwards

but he is moving in a different

direction from the force applied

work is done when the force applied to

the object

causes the object to have a displacement

in the same direction as the force

applied

the symbol for work is a capital w

the work done by a force can be

calculated using this formula

work equals to force times displacement

as we have learned in the previous

module the unit of force

is kilogram meter per second squared

or newton and the unit of displacement

is meter hence the unit for work

is the unit of force times the unit of

displacement

or newton meter otherwise known as joule

[Music]

the unit joule is named after the

english physicist

james prescott joel this is also a unit

of energy

one joule is equal to the work done or

energy expended in applying a force of

one newton through a distance of one

meter

let's try calculating for work done

suppose you are pushing a chair

with a 500 newton force along a seven

meter aisle

how much work is done in pushing the

chair

from one end of the aisle to the other

so we have the formula

work is equal to force times

displacement

the given force is 500 newton and

the displacement is 7 meters so the work

done

is 500 newton times 7 meters

which is equal to 3 500 newton meters

or 3 500 joules

try doing this simple activity play a

bowling game

roll a plastic or rubber ball along the

floor to hit some empty plastic bottles

or bowling pins

is there work done in the ball what can

a moving ball do the answer is yes

you have done work on the ball the force

you exerted

in pushing the ball is in the same

direction as the motion of the ball

but then you did not continuously push

the ball

until it hit the empty bottles or

bowling pins

you just gave it a nudge and then it

rolled forward

the force exerted on the ball changed

the ball's motion

something was transferred to the ball

causing it to move continuously

that something is called energy

the energy became the motion energy of

the ball

now let's wrap things up work is done

when the force applied to the object

causes the object to have a displacement

in the same direction as the force

applied

that's all for now see you on our next

video

and don't forget to keep your minds busy

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