Forces In Action
Gravity is the force in which a planet or
other body draws objects towards its center. The force
of gravity keeps the planets orbiting around the Sun.
Earth's gravity is what keeps people on the
The gravitational pull of the moon drags the seas towards it,
making ocean tides. Gravity isn't always the same. In some
places, it is stronger as there is more mass underground.
Black holes have so much mass that their gravity is strong enough to keep anything, including light, from escaping.
Friction is a force between two surfaces that are sliding across each other. This force always works in the opposite direction in which the object is moving. The amount of friction is down to what the material is made out of. If the surface is rough, the more friction there will be, the smoother the surface, the less friction is will have. Also, if you rub your hands really quickly, you will get warmer, which is also names as friction.
Water and Air Resistance
Air resistance is a type of force between air and any other material.
Water resistance is a force acting on an object floating through water. If you go swimming, there are water particles between your skin. For air resistance, if an aeroplane is flying through the air, some air particles can hit the plane, making it more difficult for it to move through the sky.