Question

Please answer it fast.

Physics
( Newton's laws of motion)

9. Principle of rocket is
a) Newton's I law of motion
b) Newton's third law of motion
c) Law of conservation of linear momentum
d) Law of conservation of energy

10.A block of wood floats with 4/5 of its volume inside water but just floats in an oil. The density of the oil
is (given that density of water is 1 gcc - 1)
a) 400 kg/m
b) 800 kg/m
c) 200 kg/m
d) 600 kg/m

11. A sphere of density d is allowed to fall in a liquid of density d/4. The acceleration of the body is
a) g/4
b) 3g/4
c) g/2
d) g

12. A machine gun fires 20 bullets per second into a target. Each bullet weighs 150 g and has a speed of
800 m/s. The force necessary to hold the gun is
a) 800 N
b) 1000 N
c) 1200 N
d) 2400 N

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Answer 1

Answer:

d. 2400 N in 12 a.g/4 in 11