DC electricity is the force here.
The battery help to get something which is electric to get the power.
You should definitely use a power saw with a guide to saw a straight line. Straight lines can be very difficult with a regular saw and will be much easier for you with a guide.
Most Power wheelchairs use battery power not servo motors. These batteries are provided by many companies and are available online or in stores.
no, but you do need a power source, such as a cell or a power pack if you do not want to use a battery.
power cord
lots
You will need to use the power cord and/or the battery in order to turn the laptop on.
use your pencilcase for this one
You would use a drill, a sabre saw and possibly a reciprocating saw.
When the phone is turned off, the battery provides a trickle of power to maintain the memory in the phone.
Yes, the cassette is inserted into your car stereo which uses power from the battery.
No, In a hydroelectric system force of water rotates a dynamo that generates power. The power must be used or stored in a battery. If the battery is dead you cannot store power.