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leena19
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Homework Statement
A ship which is at rest,is connected to land by a chain.The ship is powered by 2 propellers.When the ship is moving ,the 2 propellers push the water backward with velocity 20ms-1,relative to the earth.density(dw)of seawater is 1000kgm-3.Total mass of the ship(M)is 2*107kg
(1)The effective area swept by the blades of a propeller is 12m2,calculate the mass of water pushed in 1 second.
(2) Calculate the force exerted on the 2 propellers by water
(3) what is the initial acceleration (a)of the ship if the chain is released?
(4) goods of weight 4*106kg are unloaded from the ship at a harbor.Cross sectional area of the ship base is 1000m2.Assuming the hull of the ship is vertical,cal.the height raised by the unloading
(5) As the ship is raised,there's a danger of it falling to a side.how much volume of water must be taken into submerge it to the previous level?
(6) The ship is loaded back with new goods & the water taken in is removed,before it starts sailing.Height submerged in the water is 5m.Due to a blast,a small hole is formed at the base.find the initial speed of water entering the ship?
(7) water enters the ship at the rate of 10m3s-1,and the height of the ship is 8m.calculate the time taken for the ship to submerge fully
(8) once the ship is fully submerged it reaches the sea bottom.If the average density of the material of the ship is 2500kgm-3.Cal the min,force requied to bring the ship back to the surface
Homework Equations
The Attempt at a Solution
I'm sorry the question's so long.
It seems like a very easy question and I managed to do it upto (6).
(1) Volume of water pushed out/s = Au
12*20*2=480m3s-1
massof water/s=dw*V
1000*480kgs-1
(2) [tex]\stackrel{\rightarrow}{F}[/tex] = ma
F=m/t(v-u)
480*1000*20= -9.6*106N
(3) [tex]\stackrel{\rightarrow}{F}[/tex] = ma
-9.6*106/2*107 = a
= -0.48ms-2
(4) P = F/A
hdg = 4*107/1000
h=4m
(5) V= A*8
=8000m3
(6) P1 at the bottom of vessel = pi + 5dg
P2=pi=atmosphric pressure
(P1-P2)A = m(v-u)/t
5*104*103= m(v-u)/t
It's here that I'm stuck,i don't know how to proceed without m/t,I'd like to think the m/t here is the same as what i got in (1),but i don't think that's possible.
Hope someone can help.
THANK YOU