What is Work?

S4-SA1-0009

Grade Level:

Class 6

Space Technology, EVs, Climate Change, Biotechnology, HealthTech, Robotics, Chemistry, Physics

Definition

What is it?

In science, Work is done when a force causes an object to move a certain distance in the direction of the force. It means energy is transferred from one place to another. If there's no movement, no work is done, even if a lot of force is applied.

Simple Example

Quick Example

Imagine you are pushing your school bag across the floor. If the bag moves from one spot to another because you pushed it, then you have done work. If you push the wall with all your might but the wall doesn't move, then no work is done, even though you feel tired!

Worked Example

Step-by-Step

Let's say you push a cart at the grocery store. You apply a force of 50 Newtons (N) and the cart moves 10 meters (m).

1. Identify the force applied: Force (F) = 50 N.
2. Identify the distance moved: Distance (d) = 10 m.
3. Recall the formula for work: Work (W) = Force (F) × Distance (d).
4. Substitute the values into the formula: W = 50 N × 10 m.
5. Calculate the result: W = 500 Newton-meters (Nm).
6. State the unit of work, which is Joules (J): W = 500 Joules.

Answer: You have done 500 Joules of work.

Why It Matters

Understanding work is crucial for engineers designing electric vehicles (EVs) to know how much energy is needed to move a car, or for robotics engineers programming a robot arm to lift objects. It helps us build efficient machines and understand how energy is used in everything from space technology to health-tech devices.

Common Mistakes

MISTAKE: Thinking that effort or feeling tired means work is done. | CORRECTION: Work is only done if there is movement (displacement) in the direction of the applied force.

MISTAKE: Forgetting that the movement must be in the direction of the force. | CORRECTION: If you carry a heavy school bag horizontally, you apply upward force against gravity, but the bag moves forward. No work is done by your upward force against gravity in the direction of motion.

MISTAKE: Using incorrect units for work. | CORRECTION: The standard unit for work is Joules (J), which is equivalent to Newton-meters (Nm).

Practice Questions

Try It Yourself

QUESTION: A boy pushes his toy car with a force of 10 Newtons, and it moves 2 meters. How much work is done? | ANSWER: Work = Force x Distance = 10 N x 2 m = 20 Joules.

QUESTION: A weightlifter lifts a 100 kg barbell 1.5 meters high. If the force needed to lift it is 980 Newtons, how much work is done? | ANSWER: Work = Force x Distance = 980 N x 1.5 m = 1470 Joules.

QUESTION: A delivery person carries a parcel weighing 5 kg for 50 meters on a flat road. Then, they lift it onto a shelf 1 meter high. How much work is done in carrying the parcel horizontally, and how much work is done lifting it? (Assume force to lift 5 kg is 49 N). | ANSWER: Work done carrying horizontally = 0 Joules (force is upward, motion is horizontal). Work done lifting = Force x Distance = 49 N x 1 m = 49 Joules.

MCQ

Quick Quiz

When is work said to be done?

When a force is applied, but the object does not move.

When an object moves, but no force is applied.

When a force causes an object to move in the direction of the force.

When an object is held stationary against gravity.

The Correct Answer Is:

Work is only done when a force causes movement (displacement) of an object in the direction of the applied force. Options A, B, and D do not meet this condition.

Real World Connection

In the Real World

Think about the construction workers building a new flyover in your city. When a crane lifts heavy steel beams, it is doing a lot of work against gravity. Similarly, when a delivery person on a bicycle pedals to move their bike and deliver your online order, they are doing work to overcome friction and move forward.

Key Vocabulary

Key Terms

WORK: The energy transferred when a force moves an object over a distance. | FORCE: A push or a pull on an object. | DISTANCE: How far an object moves. | JOULE: The standard unit of work. | DISPLACEMENT: The change in position of an object.

What's Next

What to Learn Next

Great job understanding Work! Now that you know what work is, you're ready to learn about 'Energy'. Energy is the ability to do work, so understanding it will help you see how work and energy are closely linked in the world around us.