When using power tools, never engage the trigger lock. Before replacing parts such as bits, blades, or discs on any tool, you must disconnect the power source. Most hammer drills will not hammer until pressure is applied to the drill bit. A pneumatic drill is commonly used when there is no source of electricity.
Doubling the linear dimensions (side lengths) of any figure doubles its perimeter and quadruples (x 4) its area. If its a 3-D (solid) figure, its volume multiplies by 8 .
