BASIC CONCEPTS OF FRICTION
What is friction?
Friction is a force that opposes the motion of an object when it moves over another surface.
What is the main reason friction occurs between two surfaces?
Due to irregularities present on the surfaces.
Name one factor on which friction depends.
Nature of surfaces in contact.
Why do bicycle tyres have grooves?
To increase friction and prevent slipping.
What will happen if friction suddenly disappears?
We cannot walk or control motion.
Why does a rolling ball stop after some time on the ground?
Because friction acts between the ball and the ground and slows it down.
What happens when two rough surfaces come in contact?
Their irregularities lock into each other and resist motion.
On which surface will friction be more: sand or glass? Why?
Sand, because it is rough.
Why do we use brakes in vehicles?
To increase friction and stop motion.
Why does a box stop after sliding on a table?
Because friction opposes its motion.
In which direction does friction act?
Friction always acts opposite to the direction of motion.
Why does even smooth-looking surfaces produce friction?
Because they also have tiny irregularities.
Why does an object travel a longer distance on smooth floor?
Because friction is less.
Why is it difficult to walk on a wet floor?
Because friction is less.
Why is friction useful in writing with a pencil?
It allows graphite to stick to paper.
Why is friction called a contact force?
Because it acts only when two surfaces are in contact.
Why does friction increase on rough surfaces?
Because rough surfaces have more irregularities.
Why does an object stop sooner on rough surfaces?
Because friction is greater.
Why do athletes wear spiked shoes?
To increase friction for better grip.
Why is friction sometimes harmful?
It causes wear and tear of objects.
What happens to motion if friction did not exist?
Objects would keep moving and would not stop easily.
Why is friction less on polished surfaces?
Because they have fewer irregularities.
How does changing surface type affect motion of an object?
It changes the amount of friction acting on it.
Why are aeroplanes and ships given special shapes?
To reduce friction with air or water.
Why do we apply oil to machine parts?
To reduce friction.