What is friction? In which direction does it always act?

Name the three main types of friction in the order they are encountered when starting to move an object.

State the two factors that the magnitude of limiting friction depends on.

A student claims that a wider tyre will have more friction than a narrower tyre of the same object. Is this student correct? Explain.

Give two examples where friction is advantageous (useful).

Give two examples where friction is disadvantageous (a problem).

Name one method used to reduce friction in machinery.

Which is usually greater: limiting friction or dynamic friction?

Why is it difficult to walk on a very smooth, icy surface?

What is the role of the treads on a car tyre?

Define static friction. Why is it considered a variable force?

Explain how brakes on a bicycle work, mentioning the role of friction.

An object is pushed with a force of 10 N but does not move. What is the magnitude of the static friction force?

How does lubricating surfaces with oil reduce friction?

An object weighing 50 N rests on a table. If a heavier object weighing 100 N is placed on top of it, what will happen to the limiting frictional force?