I'm in my spaceship in the space. I see a chunk of rock of mass 1 Kg
hovering outside my spaceship. I go out and apply a force of 5 newtons
on it and send it hurtling indefinately into outer space.

1. Is it possible to calculate the work done from the above info ? If
not can we atleast predict the order of work done (i.e in nanojoules,
joules or Gigajoules etc..) ?

2. If it is known that I had applied the force on the body for 0.01
seconds, is it now possible to know the work done? If not, what
additional info is/are required?

"Pathikrit" wrote in message om...
I'm in my spaceship in the space. I see a chunk of rock of mass 1 Kg
hovering outside my spaceship. I go out and apply a force of 5 newtons
on it and send it hurtling indefinately into outer space.

1. Is it possible to calculate the work done from the above info ?

No, you need more information.

If
not can we atleast predict the order of work done (i.e in nanojoules,
joules or Gigajoules etc..) ?

Only if you can make some kind of estimate of the time
the force was applied for or the distance travelled by the
particle while the force was being applied.


2. If it is known that I had applied the force on the body for 0.01
seconds, is it now possible to know the work done?

Yes. That is a fairly simple calculation.

Martin Hogbin

Pathikrit wrote:
I'm in my spaceship in the space. I see a chunk of rock of mass 1 Kg
hovering outside my spaceship. I go out and apply a force of 5 newtons
on it and send it hurtling indefinately into outer space.

1. Is it possible to calculate the work done from the above info ? If
not can we atleast predict the order of work done (i.e in nanojoules,
joules or Gigajoules etc..) ?

2. If it is known that I had applied the force on the body for 0.01
seconds, is it now possible to know the work done? If not, what
additional info is/are required?
--------------------------------------------------------------------
1. No

2. F=ma,s=1/2 at^2,W=Fs

Next time do your homework alone.

mw
--------------------------------------------------------------------

Pathikrit wrote:

I'm in my spaceship in the space. I see a chunk of rock of mass 1 Kg
hovering outside my spaceship. I go out and apply a force of 5 newtons
on it and send it hurtling indefinately into outer space.

1. Is it possible to calculate the work done from the above info ? If
not can we atleast predict the order of work done (i.e in nanojoules,
joules or Gigajoules etc..) ?

2. If it is known that I had applied the force on the body for 0.01
seconds, is it now possible to know the work done? If not, what
additional info is/are required?



Key--The definition of work
http://hyperphysics.phy-astr.gsu.edu/hbase/wcon.html

Newton's Second Law
http://scienceworld.wolfram.com/phys...SecondLaw.html

"Pathikrit" wrote in message
om...
I'm in my spaceship in the space. I see a chunk of rock of mass 1 Kg
hovering outside my spaceship. I go out and apply a force of 5 newtons
on it and send it hurtling indefinately into outer space.

1. Is it possible to calculate the work done from the above info ? If
not can we atleast predict the order of work done (i.e in nanojoules,
joules or Gigajoules etc..) ?

2. If it is known that I had applied the force on the body for 0.01
seconds, is it now possible to know the work done? If not, what
additional info is/are required?

Doubt is correct. I guess you are in doubt that you can finish high school.
So am I.

Marcus Wellpoth wrote in message ...
Pathikrit wrote:
I'm in my spaceship in the space. I see a chunk of rock of mass 1 Kg
hovering outside my spaceship. I go out and apply a force of 5 newtons
on it and send it hurtling indefinately into outer space.

1. Is it possible to calculate the work done from the above info ? If
not can we atleast predict the order of work done (i.e in nanojoules,
joules or Gigajoules etc..) ?

2. If it is known that I had applied the force on the body for 0.01
seconds, is it now possible to know the work done? If not, what
additional info is/are required?
--------------------------------------------------------------------
1. No

2. F=ma,s=1/2 at^2,W=Fs

Next time do your homework alone.




--------------------------------------------------------------------

Hey, I'm not THAT stupid. I HAD figured the answer.
But, sorry I didnt explain my doubt completely. My doubt is this :-

1. Energy released in burning 1 ml ( a very small amount)of H2 :- 400
joules
2. Loss in Potential energy of a 2 Kg mass when it comes down by 1 cm
(a very small distance) :- 0.2 joules
3. Work done in moving a 1 Kg block on a rough surface (k = 1)
without acceleration for a small distance (say again 1 cm) :- 0.1
joules
etc.

But the answer to the above question is :- 0.000125 joules. Is'nt that
VERY less compared to the above 3 examples? So, is'nt it a bit
counter-intuitive? Having known the above 3 figures, one would expect
the work done to be much more than calculated.

"Pathikrit" wrote in message
om...
I'm in my spaceship in the space. I see a chunk of rock of mass 1 Kg
hovering outside my spaceship. I go out and apply a force of 5 newtons
on it and send it hurtling indefinately into outer space.

1. Is it possible to calculate the work done from the above info ? If
not can we atleast predict the order of work done (i.e in nanojoules,
joules or Gigajoules etc..) ?

You need to know the distance, delta_x, or time, delta_t,
over which the force, F, is applied. The standard way
of describing this is to give the rock an "impulse" which
means a change in momentum, delta_p

delta_p = m*delta_v = F*delta_t

where delta_v is the rocks change in velocity and m
is the rock's mass. The rock's final kinetic energy,
m*v^2 / 2 is equal to the work done on the rock.

Work = m*v^2 / 2 = F*delta_x

2. If it is known that I had applied the force on the body for 0.01
seconds, is it now possible to know the work done? If not, what
additional info is/are required?

Yes. delta_p = m*delta_v = F*delta_t

[Old Man]

On 8 Jun 2004 09:02:53 -0700, (Pathikrit)
wrote:

I'm in my spaceship in the space. I see a chunk of rock of mass 1 Kg
hovering outside my spaceship. I go out and apply a force of 5 newtons
on it and send it hurtling indefinately into outer space.

1. Is it possible to calculate the work done from the above info ? If
not can we atleast predict the order of work done (i.e in nanojoules,
joules or Gigajoules etc..) ?

2. If it is known that I had applied the force on the body for 0.01
seconds, is it now possible to know the work done? If not, what
additional info is/are required?
The work done depends on the mass of the spaceship also. You apply
force F for time T equally to m and M.
FT/M = P1 momentum (ship)
FT/m = P2
The work done is p^2/2m:
W1 = P1^2/2M
W2 = P2^2/2m
So if M is anything but infinity, you will be doing additional work on
the spaceship, W1 being W2 x m/M.

Mr. Dual Space
(If you have something to say, write an equation.
If you have nothing to say, write an essay).

(Pathikrit) wrote:

I'm in my spaceship in the space. I see a chunk of rock of mass 1 Kg
hovering outside my spaceship. I go out and apply a force of 5 newtons
on it and send it hurtling indefinately into outer space.

1. Is it possible to calculate the work done from the above info ? If
not can we atleast predict the order of work done (i.e in nanojoules,
joules or Gigajoules etc..) ?

of course not, there's information missing.

2. If it is known that I had applied the force on the body for 0.01
seconds, is it now possible to know the work done? If not, what
additional info is/are required?

if the force is applied for 0.01s in the same direction, on the center
of gravity of the body it is possible. And very easy to calculate.

F=m*a is quite a useful formula...

the rest is an exercise for the reader :-))

(Pathikrit) wrote in message om...
Marcus Wellpoth wrote in message ...
Pathikrit wrote:
I'm in my spaceship in the space. I see a chunk of rock of mass 1 Kg
hovering outside my spaceship. I go out and apply a force of 5 newtons
on it and send it hurtling indefinately into outer space.

1. Is it possible to calculate the work done from the above info ? If
not can we atleast predict the order of work done (i.e in nanojoules,
joules or Gigajoules etc..) ?

2. If it is known that I had applied the force on the body for 0.01
seconds, is it now possible to know the work done? If not, what
additional info is/are required?
--------------------------------------------------------------------
1. No

2. F=ma,s=1/2 at^2,W=Fs

Next time do your homework alone.




--------------------------------------------------------------------

Hey, I'm not THAT stupid. I HAD figured the answer.
But, sorry I didnt explain my doubt completely. My doubt is this :-

1. Energy released in burning 1 ml ( a very small amount)of H2 :- 400
joules
2. Loss in Potential energy of a 2 Kg mass when it comes down by 1 cm
(a very small distance) :- 0.2 joules
3. Work done in moving a 1 Kg block on a rough surface (k = 1)
without acceleration for a small distance (say again 1 cm) :- 0.1
joules
etc.

But the answer to the above question is :- 0.000125 joules. Is'nt that
VERY less compared to the above 3 examples? So, is'nt it a bit
counter-intuitive? Having known the above 3 figures, one would expect
the work done to be much more than calculated.

First, I think you need to check the answer you got. I think
you skipped a digit.

Second, you are comparing the work to various things. Yet you
don't seem to have a clue whether these are appropriate or not.
1) For Hydrogen, I have not checked your figure. But so what?
If you exploded 1ml of H2, how fast would you expect it to
push your 1kg block? And how fast does it finish going?
2) How far does the 1kg mass move during the time you are
pushing? And what force is involved in "when it comes down?"
3) What frictional force is involved in pushing that block 1cm?
And how far did your block go in the original question?

If you pick up on these, I think you will see that these should
be much larger since they involve much larger distances, or
much larger changes in velocity.
Socks