Forces in Action - What makes things fall?
What makes things fall?
Gravity is the force that makes things fall. It is caused by the enormous size of the Earth pulling everything on its surface, or in its atmosphere, towards it. When a stone is dropped in the air, gravity pulls the stone down. Without gravity objects would float in the air.
Why do things float or sink?
Things in water float or sink depending on 'buoyancy'. Buoyancy is the balance between gravity pulling things down and up thrust. Upthrust is the force of water pushing upwards on an object. An aircraft carrier floats because upthrust on its wide hull is greater than the pull of gravity on its great weight.
How does a boat shape help it go faster?
A boat with a sharp, pointed front can go faster than a flat-fronted boat because there is less water resistance. Water resistance is the friction between water and an object moving through it. A boat with a pointed front end allows the water to flow past it easily and smoothly.
Did you know? Maglev trains have no wheels, they move above special tracks using the pushing force of magnetism.
How do fridge magnets work?
Fridge magnets stick to metal because of the force of magnetism, which pulls them onto the fridge. Magnetism can be caused by tiny particles called electrons moving from atom to atom in magnetic metals such as steel. It can also be caused by a force in a magnet's electron's called spin. A fridge magnet is pulled towards, or attracted to, the metal door of the fridge because of the spin in its electrons.