Two Ways to Triple the Work
Start by lifting bags.
↳ Both the force and the distance count, in proportion.
📚 Chapter Learning Kit
Work, Energy, and Simple Machines · Class 9 Science
English 5 topics 260 leveled MCQs 110 flashcards 4 games Free
Shared by a Veda teacher · Generated with Veda AI · Oct 2026
⚡ Veda Bites
💡 Key Idea
📖 Definition
⭐ Important Fact
📖 Definition
📖 Definition
⭐ Important Fact
The whole idea, one bite at a time
Veda Bites are swipeable micro-lessons — each one teaches exactly one idea. Here's a taste from this kit; the app has the full deck.
Work Defined
The scientific meaning.
Force applied × displacement in the direction of that force.
↳ Force times distance along the force.
Name the Agency
Always say whose work, on what.
Describing work means naming both the force or agency doing it and the object it is done upon.
↳ The goalkeeper and the ball each do work on the other.
Energy Defined
What a thrown ball has acquired.
Whatever can do work on something else is said to have energy.
↳ Work done on something leaves it able to do work itself.
The Work-Energy Theorem
The link between the two ideas.
Work done on an object = change in its energy.
↳ Work in, energy up.
Where It Applies
Why the theorem is worth having.
↳ It settles problems that would otherwise be awkward.
📖 Smart notes
What you'll study, topic by topic
1
Work Done by a Constant Force
In science, work means a force multiplied by the distance moved along it — so pushing a wall that will not budge is no work at all, however tiring. Get the directions right and work can come out positive, negative or exa…
- Lifting a 5 kg wheat bag one metre calls for an upward force matching $mg$, and since the bag then moves one metre along that force, everyda…
- Raising three such bags one after another to the same height amounts to three times the work, and a machine doing it would burn three times…
- Raising all three together needs a force three times as large over the same distance, and the work again comes to three times that for one b…
~40 min · full explanation, examples & memory tricks in the app
2
The Work-Energy Theorem, Forms of Energy, and Kinetic Energy
Do positive work on something and it gains the capacity to do work of its own — that capacity is energy, and the two are linked by a single theorem. Following it through gives the energy a moving body carries,…
- A thrown cricket ball knocks the wicket over and a raised flowerpot can damage whatever lies below it, so each has acquired the capacity to…
- Anything with the capacity to do work is said to possess energy, and the ball got its energy from the work the fielder did in throwing it, t…
- Positive work done on an object makes it gain energy, which it can then spend applying a force to something else and setting it moving, so p…
~50 min · full explanation, examples & memory tricks in the app
3
Potential Energy
A stretched slingshot, a bent bow and a raised ball all hold energy they have not yet spent — stored either in a changed shape or in how far apart two attracting bodies have been pulled. For a lifted object the stored am…
- Release a stretched slingshot band and whatever it touches shoots forward, and release a drawn bow and the arrow flies off as the bow spring…
- In each case the released band or bow pushes on the object it touches, setting it moving and giving it kinetic energy it did not have before…
- That energy has to have come from the stretched band or the bent bow, which held a capacity to do work purely on account of their shape.
~40 min · full explanation, examples & memory tricks in the app
4
Conservation of Mechanical Energy, and Power
As a body falls, what it loses in height it gains in speed, and the two together never change — a fact that answers questions Newton's laws would make laborious. Power is the separate question of how quickly the work get…
- Mechanical energy is the sum of a body's kinetic and potential energies taken together.
- A mass lifted to a height $h$ and let go starts with $mgh$ of potential energy, no kinetic energy at all, and so a mechanical energy of…
- After falling freely for a time $t$ its velocity has reached $gt$ and its height has dropped to $h - \frac{1}{2}gt^2$, both from the kinemat…
~45 min · full explanation, examples & memory tricks in the app
5
Simple Machines: Pulley, Inclined Plane and Lever
No machine can reduce the work a job takes, but a pulley, a ramp or a lever can change how hard you must push and in which direction. Each buys a smaller force at the price of a longer distance, and the ratio of load to…
- The total work a task demands cannot be reduced, but it can be made easier by altering the size or the direction of the force needed, and th…
- The force applied to a machine is called the effort and the force to be overcome is the load, while the mechanical advantage is the ratio of…
- A pulley is a grooved wheel that keeps a rope running true; fixed in place, it alters the direction of your pull and not its size.
~45 min · full explanation, examples & memory tricks in the app
❓ Leveled MCQ practice
Try the smart MCQs from this kit
260 questions laddered from warm-up to topper-level, each with an explanation. A taste:
Work done by a constant force is defined as:
Beginner
A the force divided by the displacement along it
B the displacement divided by the force applied
C the force multiplied by the time it acts for
D the force multiplied by the displacement along that force
Show answer & explanation
the force multiplied by the displacement along that force
Only the displacement along the force counts.
The SI unit of work is the:
Beginner
A newton, which is the SI unit of force instead
B joule, whose symbol is the capital letter J
C metre, which is the SI unit of length instead
D watt, which belongs to a later part of the chapter
Show answer & explanation
joule, whose symbol is the capital letter J
Its symbol is the capital J.
One joule is the work done when a force of one newton displaces an object:
Beginner
A one metre at right angles to it
B one centimetre along that force
C any distance at all
D one metre along that force
Show answer & explanation
one metre along that force
That gives $1\ \text{J} = 1\ \text{N} \times 1\ \text{m}$.
In base units, one joule equals:
Beginner
A $1\ \text{kg m s}^{-2}$
B $1\ \text{kg m}^{-2}\ \text{s}^{2}$
C $1\ \text{kg m}^2\ \text{s}^{-2}$
D $1\ \text{kg m}\ \text{s}^{-1}$
Show answer & explanation
$1\ \text{kg m}^2\ \text{s}^{-2}$
Substituting the newton into $1\ \text{N} \times 1\ \text{m}$ gives it.
🃏 Flashcards
Tap a card to flip it
110 flashcards in this kit — the app reviews them with spaced repetition so the right card returns on the right day.
🎮 Learning games
Play your way through this kit
Every game is built from this kit's own content — scores feed your mastery, so playing counts as studying.
Word Match
True False
Fill Blank
Word Scramble
Playable in the app
Study it properly — free, in the app
The full Veda Bites deck, complete notes, spaced-repetition flashcards, leveled MCQs, tests and games for this kit — plus Daily Facts and the Arena, every day.