A Christmas Story
A Christmas Story (1983)

 

Concept featured in film: Recoil velocity and Newton's Third Law

Location of clip: 1:22:23 - 1:24:26 (DVD)


Play Flickclip Here

Summary of clip: This film depicts young Ralphie Parker's Christmas quest for a Red Rider BB Gun. Ralphie's request is met with a "You'll shoot your eye out" by his mother, his teacher, and his last hope, Santa Claus. The clip featured here shows an ecstatic Ralphie in his backyard on Christmas morning. Ralphie is taking aim with is Red Rider BB Gun, shoots, and the recoil of the gun breaks his eyeglasses and leaves a red mark on his face.


Connection of flick to concept: Almost every high school physics textbook has the obligatory gun recoil problem at the end of the chapter on the conservation of momentum and Newton's Third Law.

Suggestions to teachers

 

1. Ask students to draw a free-body diagram depicting the forces acting on the BB and BB-gun system at the instant it is fired.

2. Ask students to explain, using their knowledge of conservation of momentum, why it is safer to get hit with the gun after recoil than it is to get hit by a bullet with a velocity, v.