We are dealing with electricity so someone may get an electric shock or in severe cases, they may get electrocuted.
Be aware of surroundings, do not close the switch when building the setup. Make sure hands are dry before dealing with wires and power source. When power is switched on, do not touch the bare ends of the wire.
Someone may carelessly put his hands near the ruler piece while the motor spins it, so the ruler piece may hit the person’s hand and injure him.
Do not put hand close to the motor when it is turned on.
If you need to be close for measurement, make sure body parts do not face the edges of the wooden ruler piece.
We will be sawing and drilling the wooden ruler and may injure ourselves and other people if we are not careful.
Be alert and also look around and assess if there is danger, before sawing or drilling. Be focused, do not swing the saw or drill around for fun, especially when people is near you. Wear safety goggles.
We may accidentally short the battery by accident by accidentally connecting the wires of the battery together. This would boil the chemicals in the battery and set the battery holder on fire.
Be alert, when not using the battery holder, do not load it with batteries. If using the battery holder, make sure wires are not connected directly together, before closing the switch.
Unlikely and not severe harm
Likely but not severe OR Unlikely but severe
Likely and Severe harm