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 CSS Forums a small question of eds.

#1
Saturday, October 23, 2010
 38th CTP (IG) Join Date: Dec 2009 Location: on your nerves Posts: 475 Thanks: 228 Thanked 341 Times in 227 Posts
a small question of eds.

As we know that the earth is rotating at a very high angular velocity and as we are on the earth and also rotating with the same speed so the net speed we feel is zero.
Now suppose there is a car and a man standing on roof of the car.car is running.Now man is at rest with respect to the car,as is the case with a man standing on the surface of the earth.Now if the man on the roof of the car jumps upwards in the air the car will move forward and he will fell on the earth behind the car.It means he will not be on the same point where he was before the jump.Now if the man on the surface of the earth jumps in the air why he comes back on the same spot and the earth does not move away from him and he doesn't fell due to inertia ?
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#2
Saturday, October 23, 2010
 40th CTP (DMG) Join Date: Jan 2007 Location: Inaccessible Posts: 1,012 Thanks: 1,335 Thanked 2,470 Times in 622 Posts
Interesting

waiting for the explanations to come from old hands at physics.
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#3
Sunday, October 24, 2010
 Senior Member Join Date: Feb 2010 Location: Lahore Posts: 174 Thanks: 23 Thanked 101 Times in 62 Posts

A man who jumps over the car roof top will fall behind because of the force exerted by the air. While on the roof top one can balance himself to cut through the air but when the air friction will increase, as a result of a jump, this force will push him backward.

Since earth's gravitational force is greater and can keep both the air and the person intact with the earth's surface, the person is not thrown back.
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#4
Tuesday, November 09, 2010
 Junior Member Join Date: Jun 2010 Location: Islamabad Posts: 13 Thanks: 7 Thanked 9 Times in 6 Posts
@ Musa

You are confusing the concept here.

1. In the 1st case person and earth are in question
2. In 2nd case person, car and earth are involved so no similarity.

Now, If in the first case a person jumps from the earth to some other heavenly body his location will be changed
#5
Tuesday, November 09, 2010
 Junior Member Join Date: Oct 2010 Posts: 9 Thanks: 0 Thanked 2 Times in 2 Posts

Who said to you that the person will fall behind the car. He will definitely fall on top of the moving car on which he jumped.however there will be some effect of air resistance.
#6
Tuesday, November 09, 2010
 Senior Member Join Date: Nov 2009 Posts: 221 Thanks: 182 Thanked 144 Times in 101 Posts

mr minhas has right concept...

there is term called relative spd... when one jumps frm earth he's jumping in relation to spd of earth n his own... these two spds resultantly bring him back to same point of origin.

in case of someone jumping from top of roof of car, phenomenon is little changd where one jumps in relation to spd of car, earth n his own... tht results for a guy to fall backward of the car...

now let me clear it otherway discarding earth's movement... wt happens to someone jumping inside of moving train or plane.. he returns to a point where he jumped frm.. wt hppns to fly flying inside of a moving train, it kps flying wth its spd n nvr collides wth the walls of train... now similarly if one jumps inside of car, instead of jumping from top of car/train/plane, he will fall exactly on same point where he startd frm.. in all these cases one jumps or moves wth direct relation to the movement of othr moving body.. bt when one jumps directly exposed to car/plane/train n earth... he will fall on a point tht will be resultant of all movements of all three bodies.. so in case of car above in question, the resultant is backward involving car's spd, man's spd, earth's spd n effect of wind to some extent..

hope it gvs some idea.. ciao
#7
Saturday, December 25, 2010
 Member Join Date: Aug 2010 Posts: 33 Thanks: 42 Thanked 15 Times in 10 Posts

there are certain things u r ignoring first of all the massive g with respect to the particular point from where the person is jumping in the latter case.

2nd the definite difference of air resistence that is present above the car.

3rd the very slow speed of the point of the earth.its like the concept of angular velocity.
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