g Problem 5. A 100 g firecracker is launched vertically into the air and explodes into two pieces at the peak of its trajectory. If a 72 g piece is projected horizontally to the left at 20 m/s, what is the speed and direction of the other piece

At the peak, velocity of firecracker = 0

It splits into mass of m₁ = 72 g and m₂ = 28 g

Applying conservation of momentum laws

m₁ v₁ = m₂v₂

72 x 20 = 28 x v₂

v₂ = 51.43 m / s.

It will go opposite to other piece to conserve momentum ie to the right direction.