The Firing Squad Demo

The Firing Squad Demo

Every day we have to make choices. Sometimes these can be life changing. In the Firing Squad Demo the student you pick to be the target, will have to choose between two dart guns to be shot with!

One of the guns has a steel ball glued to the dart. Standing approximately ten feet from the two loaded guns he or she will need to think like a physicist to make the right choice. Both guns, being essentially identical, push the two different-mass darts with the same force. Which dart will they choose to be shot with?

Here the distinction between the inertia property of mass and its gravitational property is illustrated.


In a follow-up demo, ask the students to predict which dart would hit the ground first if fired downward at the same time from a point near the ceiling.

These two demos help to illustrate the importance mass plays in Newton’s second law when expressed as a=F/m. Ask the students to explain their predictions using this equation, noting that value of ‘F’ in the equations is the force of the springs from the identical guns while the ‘m’ in the equation is the value of the mass of the different darts.

Required Equipment
Dart Gun, 1 inch Steel Ball, Hot Glue

Recommended quantity per lab group: 2

P4-1301
Dart Gun
$3.25

Recommended quantity per lab group: 1

P1-5003
1 inch Steel Ball
$1.25

Recommended quantity per lab group: 1

Hot Glue can be used to adhere the steel ball to the dart.

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