Types of forces continued.

Gravity is another force that is always acting on us no matter where we are on Earth. It is a force that acts downwards. The strength of gravitational forces acting between two objects depends on the size of the objects and their distance apart.

For example the Sun has a greater gravitational pull then the Earth, because of its greater mass. The Earth attracts a space ship towards it, but this attraction decreases as the space ship travels further away from Earth.

Thrust is a force that propels objects forwards or upwards as in rockets..

 
Rockets generate thrust by burning fuel and producing huge quantities of hot gas. This gas escapes through the nozzle of the engines creating a huge thrust, that lifts the rocket into the sky.

 

Lift is another force that is generated by moving air. Lift is the force that allows planes to fly. It is generated by the curvature of the wing. This force depends on the surface area of the curved object and the speed with which the air moves over this surface.

See The wing .