Machines can be fueled by any kind of energy. In many machines it is easy to understand the transfer of energy into mechanical force. For example, a hammer is a simple and effective machine that allows you to transfer the force of your arm to a nail head (the “fuel” for this machine is the force of your arm). In a tape player, electrical energy is the fuel that results in a mechanical force that turns the tape. Other machines are much more complex, such as computers.
We use machines because they make many activities easier for us; they help us do things that we could not otherwise do. We use machines to make us go faster, such as bicycles, skate boards, roller blades, or cars. Machines can make you stronger, like a bottle opener which multiplies the force you apply allowing you to get the bottle top off. Machines let us put force where we want it. For instance a hammer allows you to put force exactly on the head of a nail, with more force than you could manage without the hammer.
Machines
How do machines help us?
Machines help us by doing things we cannot usually do ourselves.