Forces: Pushes or pulls that can cause an object to move, stop, or change direction. Engineering design: A systematic and iterative approach to designing objects, systems, or processes that aims to meet specific criteria and constraints. Axle: A rod or spindle passing through the center of a wheel or group of wheels, allowing them to rotate. Mast: A vertical pole on a ship or boat to which sails are attached; in this context, a similar structure on the car to support the sail. Wobbly: Unsteady or shaky, often used to describe an object that is not securely fixed in place or a wheel that does not turn smoothly.