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a projectile launcher has a mass of 3 kg. it fires a projectile of mass 0.08 kg horizontally at a speed of 300 m/s.

User Nguyendown
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No question. I'll assume you want the instantaneous speed of the projectile launcher when firing the projectile.

The projectile has a momentum equal to the product of its mass and speed.

So, p = 0.08 • 300
p = 24 kgm/s where p is the momentum of the projectile

The initial total momentum of the system was zero, so the projectile launcher must also have a momentum of 24 kgm/s after firing in the opposite direction to the projectile, due to Newton's Third Law of motion.

24 = 3 • v
v = 24/3
v = 8 m/s

Therefore the projectile launcher has a recoil speed of 8 m/s after firing the projectile.

User Max Podriezov
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