Page 115 - Viva ICSE Science 4 : E-book

Magnetic force is the force exerted by a magnet that pulls
materials like iron, cobalt and nickel towards itself. A magnet
is a piece of metal (iron, cobalt or nickel) that attracts other

magnets or objects that are made of iron, cobalt or nickel
towards it. For example, when a magnet is dipped in a bowl

that contains materials like plastic, pieces of paper and iron
nails, it attracts only the iron nails, leaving behind all the other
materials. This is because of the magnetic force that is exerted by a magnet. A magnet

has two poles in it. They are north pole (N) and south pole (S).

Frictional force is the force exerted by a surface when an object moves across it. This
force develops between two objects when they come in contact with each other. The

frictional force either slows down or completely stops the object from moving. This is
because it always acts in the direction opposite to the direction of the moving object.
Frictional force is experienced more on the rough surface than the smooth surface.

less force more force

Smooth surface—less friction Rough surface—more friction

Friction is important as it provides us the grip that is necessary for walking on the ground
as our feet and the ground are in contact. Without friction, we would slip or fall on the
ground.

TIME TO REVISE

Answer in one word.

1. It holds plants, animals and other things on earth.
2. It is necessary for walking on the ground.
3. It has two poles—north and south poles.

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