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Ricky is on a rocket ship far from any planet or sun. The 900kg rocket fires its rockets for 3.5s sec and goes from 0m/s to 50 m/s.(a)What acceleration does the rocket undergo ?(b) If 160 kg of gas is expelled from the rocket. what is the gasses acceleration ?

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vi = 50 m/s vf= 0 m/s

t = 3.5 s

m = 900kg

a) vf = vi +at

-50 = 3.5a

a) a = 14.3 m/s

b) m= 740 kg

stuck right here ?

#2

Award drives a 5000 kg car cross a bridge that inclines up at 10' above the horizontal. While going cross the bridge with an acceleration of 4 m/s2 the car encounters a m_rolling of .05. With what force does the car push on the ground in order to move forward ?

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F (per) = 49000 cos 10 = 48255.6 N

F (par) = 8508.8 N

F_net = 5000 (4) = 20000 N

F_fricton = .05 (48255.6) = 2412.8 N

F_net - F (par) - F_friction = F_apply

F_apply = 9078.4 N

Is this right /

#3

A box is sitting on the level ground U (static) = .2and it has a mass of 100 kg. A person wants to pall the box 25 m cross the room with a rope, but can only exert a force of 310 N. That person pulls the rope at 32* and fins the U (sliding) = .12. Does the box move and if so how much time does it take for that person to move across the room.

F_y = 0

F_y = n + 310sin32 – 980

Normal force = 815.7 N

F_friction = .2(815.7) = 163.14 N

F_x = 310cos32 – 163.14 = 99.7 N

Got stuck right here ?