Although forces occur naturally, they can also be produced by people or machines. Often these forces are comprised of pushes, pulls or twists. You probably use forces like these every day — like when you push a door bell, open a drawer or twist a bottle top.
We also use machines to produce forces on our behalf. Machines can be made to exert a greater force than we can produce ourselves. For example, a tractor can pull a trailer full of hay, a bulldozer can push forward a mound of earth and a potter’s wheel turns and helps to shape a vase out of a lump of clay. Look around you and you will see many forces in action.
You can exert a force by pulling. Pulling a rope attached to a sledge will make the sledge move forwards. You use many pulling forces every day-like doing up a zip, pulling the curtains, putting socks on and pulling a door closed.
Sometimes you exert a force by pushing – you can push a table across a room, push a swing door to open it, push a trolley or push a parcel through letter box. When you push and pull you use your weight to exert a force onto an object.
You can also exert a number of forces by twisting – you might wring out wet clothes to dry them, turn a wheel, open a jam jar, and turn a screw – driver or wind up a clock. Twisting forces are usually conducted with your arms and your hands.