A fireworks shell is moving straight upward at when it explodes into two fragments of…
PHYSICS · Single correct · A Level · Physics · Mechanics and materials · Mechanics and materials
Problem
A 2.0kg fireworks shell is moving straight upward at 40m/s when it explodes into two fragments of masses 1.2kg and 0.8kg. The explosion lasts 2.0×10−3s. Air resistance is negligible. Consider the system to be the two fragments only. Which of the following statements best describes the validity of applying linear momentum conservation to this system for the horizontal and vertical components?
(a) Only the horizontal component is conserved because gravity provides negligible impulse during the brief explosion, while the vertical component changes appreciably.
(b) Both components are approximately conserved because the gravitational impulse during the explosion is negligible, and no other external forces act.
(c) Both horizontal and vertical components are conserved because gravitational forces on each fragment are equal in magnitude and opposite in direction.
(d) Only the vertical component is conserved because the explosion can create horizontal momentum while gravity maintains the vertical momentum.