mcd173
A skier (m=57.0 kg) starts sliding down from the top of a ski jump with negligible friction and takes off horizontally. If h = 6.20 m and D = 13.4 m, find H.
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chand
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what is "h" ?
chand
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Use the energy method.
Decrease in potential energy= gain in kinetic energy
mg(H-h) = 1/2 mv^2 here we get the velocity.
After taking off, the range is given by
R= u. t where "t" is the time of descent and 'u' is the velocity.
chand
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Hope its clear
hosein
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(1/2)mv^2=mgD so v=sqrt(2gD)
v on above is v0 for next part of ask (when skier leave ski jump)
y=(v0^2/2*g) so H=y+h
chand
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isn't "d" the distance covered after he jumped?
hosein
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i think D is ski jump's length
hosein
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i drew above do you solve it?
chand
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D should be the range i feel.
chand
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Let us take D to be the range.
Now, decrease in potential energy would be mg(H-h) as he came down a height of H-h
So, mg(H-h) = 1/2 mv^2
v=(2g(H-h))^1/2
hosein
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question want H did you get it?
chand
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yes.
hosein
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so it is...?
chand
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approximately 15.026
hosein
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how did you get time of descent
chand
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t= {2h/g}^1/2
hosein
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this t is time of H time of descent is: 2*t
hosein
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how did you take v=u in two formula?
mg(H-h) = 1/2 mv^2
R= u. t
chand
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D= v. t where v= [2g(H-h)]^1/2 and t= [2h/g]^1/2
"t' is the time of descent from "h" to the ground.
I typed u instead of v
hosein
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u is velocity of body when it's arrive to ground but vis velocity in top of path
hosein
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no i think you use 2*t in formula for D
hosein
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hence d is all of horizontally path
chand
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|dw:1331643793186:dw|
chand
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"v' is the velocity of the man before taking off. We are not concerned about the velocity which he will have while landing on the ground
chand
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Yes "D" is the horizontal distance covered.
hosein
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did you see my diagram ? H is max height that man arrive . i didn't understand your fig
hosein
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i mean that how did you yeild to u=v
chand
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When a body takes off horizontally, the height from which it took off will be the maximum height. i took that the person slides from a height "H" and after reaching a height "h', he takes off and covers a horizontal distance 'D".
I mistyped u or v.
chand
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mistyped u for v
chand
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am i clear?
hosein
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yes you'r right