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PHYSICS HELP!!!

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nid404:
I have a few questions....test tom...plz help me out...astar plz...asap

1) A gas expands in such a way that pV2 remains constant. It starts with a volume of 6x10-3 m3 and a presurre of 30000 Pa, and ends with a volume of 13.0 x10 -3. Find the work done by the gas, either by plotting a graph or by integrating.

2) A car of mass 1200kg has a power output of 58kW when travelling at a speed of 30m/s along a flat road. what power output is required if it is to travel at the same speed up a hill with a gradient of 10%?(This is a gradient of 1 in 10. The angle of the slope is tan-1 0.10=5.7o )

3) In a tidal barrage scheme, the area of sea-water behind the barrage is 30km2, the tidal depth is 10m and the density of the sea-water is 1030 kg/m3
a) what is the energy possibly available from this scheme in one cycle of ebb and flow?
b) If one ebb and flow takes 12hrs and 40min, what avg power does this represent?
c) What practical problems are bound to occur if max energy output per cycle is to be achieved?

4) The steel cable on a crane has a diameter of 13mm. What force is necessary to to produce a strain of 0.1% in the wire?
What is the max acceleration with which it can lift a load of mass 1000kg if the strain in the cable is not to exceed 0.1%. The young modulus of the high-tension steel used is 2.4x1011 Pa. (Be certain to draw a free body diagram for the load)

Please answer them with the diagram for the last question if possible....plzzz

Thanks

nid404:
Please some1 answer this....i need ur help...make it asap...before tom...or i'll flunk the test

astarmathsandphysics:
I will answer when i get home in 2 hours

nid404:
Thank you. I will check it tom morning before leaving for school...it's 11 pm already.
I'll be happy if u do it with steps...so in the morning i won't have to figure out how u derived at the answer

Thank you once again :)

astarmathsandphysics:

--- Quote from: nid404 on August 27, 2009, 03:23:46 pm ---I have a few questions....test tom...plz help me out...astar plz...asap

1) A gas expands in such a way that pV2 remains constant. It starts with a volume of 6x10-3 m3 and a presurre of 30000 Pa, and ends with a volume of 13.0 x10 -3. Find the work done by the gas, either by plotting a graph or by integrating.

2) A car of mass 1200kg has a power output of 58kW when travelling at a speed of 30m/s along a flat road. what power output is required if it is to travel at the same speed up a hill with a gradient of 10%?(This is a gradient of 1 in 10. The angle of the slope is tan-1 0.10=5.7o )

3) In a tidal barrage scheme, the area of sea-water behind the barrage is 30km2, the tidal depth is 10m and the density of the sea-water is 1030 kg/m3
a) what is the energy possibly available from this scheme in one cycle of ebb and flow?
b) If one ebb and flow takes 12hrs and 40min, what avg power does this represent?
c) What practical problems are bound to occur if max energy output per cycle is to be achieved?

4) The steel cable on a crane has a diameter of 13mm. What force is necessary to to produce a strain of 0.1% in the wire?
What is the max acceleration with which it can lift a load of mass 1000kg if the strain in the cable is not to exceed 0.1%. The young modulus of the high-tension steel used is 2.4x1011 Pa. (Be certain to draw a free body diagram for the load)

Please answer them with the diagram for the last question if possible....plzzz

Thanks

--- End quote ---

1)NBot clear what this question means. I assume they mean integrate pdV so if pV2=K, pdV=KdV/V2

and K=30000*(6*10-3)2=1.08

=1.08(-1/13*10^-3--1/6*10^-3)=96.92J

2)p=fV SO f=p/V=58000/30=1967N

When it travels up the hill it rises by 30sin5.7o=2.985m every second
The energy needed to do this every second is mgh=1200*9.8*2.985=35104J

So new power is 58000+35104=93104W

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