Why do our leg muscles cramp when we run for a long period ?

Why a red muscle fibre can work for a prolonged period while a white muscle fibre suffers from a fatigue after a short period?

Why do edible oils show rancidity when stored for long period?

Why does our palm become warm when we rub them together?

Why does our palm feel cold when we put some acetone or petrol or perfume on it?

Why do we perfect to use a when with a long arm ?

Why do we use electricity?