Additional Info

• ID Code: C5-18
• Purpose: Demonstrate Newton's third law of motion
• Description: This small wheeled cart has a battery-powered fan mounted on it, and a slot at the end that can hold a plastic sail. With the sail off, turning on the fan drives the cart in the direction opposite the blowing air. With the sail on and the fan off, blowing on the sail will drive it in the direction you blow. With the sail on and the fan on, the sail visibly flexes, but the cart goes nowhere at all. The force acting on the sail is such that it exactly cancels.

  Note: The fan spins quite fast. Don't let it hit your fingers! To connect and disconnect power, use the alligator clip wire on the rear; clip it to the fan support frame for safety when not in use.

  Consider inviting students to make predictions about the cart's behaviour with and without the sail. Invite them to discuss the forces involved.

• Availability: Available
• References: REFERENCES: (PIRA 1H10.20)
• Loc codes: C5
• Videos-1: Moving opposite to that of the blowing air
• Videos-2: Moving in the direction of the blowing air