Start It, Steer It, Squash It
Three things a force can do.
↳ A kicked ball, a batted ball, a squeezed lemon.
📚 Chapter Learning Kit
How Forces Affect Motion · 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
⭐ Important Fact
✏️ Example
💡 Key Idea
⚖️ Comparison
📖 Definition
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.
Force Needs a Direction
A number alone will not do.
Force takes a direction alongside its magnitude and unit, exactly as position, displacement, velocity and acceleration do.
↳ Every force you have met was described with a direction attached.
Direction Was Always There
Four forces, four directions.
↳ The direction is part of naming the force.
Something Pushes Back
You pushed, and nothing happened.
Friction arises between the box's underside and the floor, acting against the force you apply.
↳ Push harder than the friction.
Four Forces on a Pushed Box
Count them all before deciding.
↳ The last two balance, so the first two decide the motion.
The Normal Force
The one you may not have named.
The push a surface exerts upward on whatever rests on it, at right angles to that surface.
↳ It balances the object's weight exactly.
📖 Smart notes
What you'll study, topic by topic
1
The Concept of Force, and Balanced and Unbalanced Forces
A force can start something moving, change how fast or which way it goes, or squash it out of shape, and it always has a direction as well as a size. Where several forces act at once, what matters is the net force: balan…
- A force can set a resting object going, alter the speed or the direction of something already moving, and even change an object's shape.
- Kicking a ball off the ground, a bat turning a cricket ball aside, and fingers squeezing a lemon show those three effects in turn.
- Every force named in earlier grades came with a direction attached: friction acting against the motion, like magnetic poles pushing apart an…
~35 min · full explanation, examples & memory tricks in the app
2
The Force of Friction
Push a box and something pushes back. Friction is why a heavy object refuses to budge until you shove harder, why a bicycle coasts to a halt, and why a stack of coins slides further on marble than on wood — and following…
- Push a resting object forward and often nothing happens until you push harder, which tells you something is pushing back.
- That something is friction, arising between the underside of the box and the floor and acting against whatever force you apply.
- The box only starts travelling once your push outweighs friction, because only then is there something left over acting forward.
~40 min · full explanation, examples & memory tricks in the app
3
Newton's First Law of Motion
Left alone, an object does nothing new: a resting one stays put and a moving one keeps the velocity it had. Only a net force changes that, which means a body coasting along at steady speed needs no force at all to keep d…
- Newton's first law holds that a body stays at rest, or keeps travelling at a constant velocity, for as long as no net force acts upon it.
- Put the other way about, where the net force on a body works out at zero it can neither begin to move nor alter the velocity it already has,…
- Saying an object is at rest is the same as saying its velocity is zero.
~35 min · full explanation, examples & memory tricks in the app
4
Newton's Second Law of Motion
Push harder and a thing speeds up more; load it heavier and it speeds up less. Two cart experiments pin those two observations down into one equation, $F = ma$, which then explains a cricketer's hands, a car's airbag and…
- A force can start something moving, halt it, or alter its velocity, and since a change of velocity is an acceleration, a force produces acce…
- Everyday experience suggests a first hypothesis: for the same object a bigger force gives a bigger acceleration, and a gentler one a smaller…
- Testing that calls for forces of different sizes on the same object and surface, which is arranged by hanging different weights, since the E…
~50 min · full explanation, examples & memory tricks in the app
5
Newton's Third Law, and Forces on a System of Objects
Forces never come singly: push on anything and it pushes back just as hard the other way. That is how you walk, how a canoe moves and how a rocket lifts off — and once several objects are tied together, treating them as…
- At least two objects have to interact before any force comes into play, which is why kicking a ball leaves your foot feeling a force from th…
- Sitting on a wheeled chair with the feet off the floor and shoving a heavy table away sends the chair backwards, while hauling the table tow…
- Each time a force went onto the table, the table put one back onto the person in the opposite direction.
~50 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:
Which of these is not something a force can do?
Beginner
A Set an object moving from rest
B Change the direction a moving object travels in
C Give an object a different mass from the one it had
D Change the shape of an object
Show answer & explanation
Give an object a different mass from the one it had
The other three are exactly what a force does.
The SI unit of force is the:
Beginner
A newton, written with a small letter and given the symbol N
B metre, which is the SI unit of length instead
C kilogram, which is the SI unit of mass instead
D second, which is the SI unit of time instead
Show answer & explanation
newton, written with a small letter and given the symbol N
It is written with a small letter and given the symbol N.
Besides magnitude and unit, what must be specified for a force?
Beginner
A Its mass
B Its temperature
C Its direction
D Its colour
Show answer & explanation
Its direction
Displacement, velocity and acceleration are quoted the same way.
Two forces equal in magnitude but opposite in direction are called:
Beginner
A unbalanced forces, which set the object moving at once
B net forces, being the single equivalent of all acting
C buoyant forces, which a liquid exerts on what floats
D balanced forces, which leave the object's motion unchanged
Show answer & explanation
balanced forces, which leave the object's motion unchanged
They leave the object as it was.
🃏 Flashcards
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110 flashcards in this kit — the app reviews them with spaced repetition so the right card returns on the right day.
🎮 Learning games
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