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Author Topic: How is work calculated?  (Read 2523 times)

Cathy Erwin

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How is work calculated?
« on: 20/11/2011 22:30:02 »
Cathy Erwin  asked the Naked Scientists:
   
Hi,

My son in grade 9 has just asked me to help him with an exam question, for his Physical Science exam, which is TOMORROW!!!

A 75kg man pushes against a 500 000 ton wall for 250 seconds. The wall does not move. How much work is done?

He says the equation is Work = force x distance

If distance is 0 then surely the answer is 0?

Please help.

Thanks and kind regards,

Cathy

What do you think?
« Last Edit: 20/11/2011 22:30:02 by _system »


 

Offline Soul Surfer

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How is work calculated?
« Reply #1 on: 20/11/2011 23:04:07 »
One should not help with homework or exam questions but what you have expressed seems to show a correct understanding of the situation
 

Offline yor_on

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How is work calculated?
« Reply #2 on: 20/11/2011 23:11:16 »
Show him this one and see what he thinks
What are "energy" and "work".
 

Offline syhprum

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How is work calculated?
« Reply #3 on: 21/11/2011 05:12:26 »
Although in the strictly technical sense no work is done the man infact is dissipating energy in his muscles generating the force that he applies to the wall.
I think after 250 seconds he will have worked up quite a sweat
 

Offline simplified

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How is work calculated?
« Reply #4 on: 21/11/2011 16:53:45 »
There is no time of moving of the wall.
 

Offline Geezer

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How is work calculated?
« Reply #5 on: 21/11/2011 18:45:45 »
There is no time of moving of the wall.

Unless you want to be powerful, it doesn't matter how much time you take to do your work ;)
 

Offline Bored chemist

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How is work calculated?
« Reply #6 on: 21/11/2011 21:31:36 »
Cathy Erwin  asked the Naked Scientists:
   
Hi,

My son in grade 9 has just asked me to help him with an exam question, for his Physical Science exam, which is TOMORROW!!!

A 75kg man pushes against a 500 000 ton wall for 250 seconds. The wall does not move. How much work is done?

He says the equation is Work = force x distance

If distance is 0 then surely the answer is 0?

Please help.

Thanks and kind regards,

Cathy

What do you think?

I think you should be pleased that he understands physics better than you .
 

The Naked Scientists Forum

How is work calculated?
« Reply #6 on: 21/11/2011 21:31:36 »

 

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