Before the bullet is fired the momentum is Zero because nothing is moving but once the bullet is shot the momentum increases because of the movement of the bullet moving forward.
A canyon is a deep ravine between pairs of escarpments or cliffs and is the most often carved landscape by the erosive activity of a river over geologic timescales. A canyon may also refer to a rift between two mountain peaks, such as those in ranges including the Rocky Mountains, the Alps, the Himalayas or the Andes.
The correct answer is:
a positron is emitted when proton converts to a neutron.
The reaction can be described as following:
₁¹p (proton) → ₀¹n (neutron) + ₁°e (positron or ₁⁰β)
Positron is an antiparticle of a β particle (₋₁°β), which means it has an oposite charge to it, but same mass.