Track quiz
Here are the eleven rules, in the words each lab uses.
| Idea | The rule |
|---|---|
| A push or a pull | A force is a push or a pull on an object. It comes from that object's interaction with another object. |
| What a force does | A force can make a still object move. It can change the speed of a moving object. It can change its direction or its shape. |
| Touching, or not | A contact force needs touching. A non-contact force acts across a gap. |
| Two at once | Forces on one line, the same way, add. Forces on one line, opposite ways, subtract. What is left is the net force. |
| Balanced | Forces are balanced when they cancel. The net force is zero. The motion does not change. |
| Unbalanced | The net force changes the motion. A net force can speed up, slow down or turn an object. |
| Friction | Friction acts against the motion, or against the push to move. Rougher surfaces give more friction. |
| Friction both ways | We need friction to grip, walk, write and stop. We reduce friction where it wastes effort or wears parts. |
| Weight and the spring balance | Weight is the pull of the Earth on an object. It is measured in newtons. For the smallest reading, divide a big gap by its equal spaces. |
| Mass stays, weight changes | Mass is the amount of matter. It is the same everywhere. Weight is the pull on an object. It changes from place to place. |
| The push a liquid gives | A liquid pushes up on an object. This push is upthrust. Weight bigger than upthrust: the object sinks. Both the same: it floats. |
You ring a bicycle bell with your thumb. What is the force?
A racket sends a ball back the way it came. What changes?
Which force acts across a gap?
A coconut falls from a palm. Which force pulls it down?
Two teams pull a cart. One pulls left with 15 N. One pulls right with 9 N. What is the net force?
A book rests on a table. What can we say about the forces on it?
A trolley moves. The net force points the same way as the motion. What happens?
One shove slides a block on tile and on a rough mat. Where does it stop sooner?
Where do we need friction?
Big marks on a balance are 2 N apart. The gap is split into 4 equal spaces. What is the smallest reading?
A bag is taken from the Earth to the Moon. What changes?
An object weighs 10 N. The water pushes up on it with 6 N. What happens?
Chapter 5 is called Exploring Forces. Read it in your NCERT book.
Next: Pressure, Winds, Storms, and Cyclones. Pressure is a force spread over an area.