## lgbasallote 3 years ago In 1990, walter arfeuille of belgium lifted a 281.5 kg object through a distance of 17.1 cm using only his teeth (a) how much work was done on the object by arfeuille in this lift, assuming the object was lifted at constant speed?

1. lgbasallote

im thinking \[-\Delta U_{GRAV}?\]

2. rajathsbhat

Right-o!

3. lgbasallote

so \[\implies -(281.5)(9.8)(0-0.171)?\] i change this to meters right?

4. rajathsbhat

5. rajathsbhat

that multiplication is the answer though..

6. lgbasallote

the given was 17.1 i was confirming that i needed to change that to meters

7. lgbasallote

or do i use 17.1?

8. rajathsbhat

ah, yes, it is 0.171 that you need you need to use.

9. lgbasallote

ahh thanks

10. CarlosGP

His work was used to increase potential energy of the weight, therefore you can calculate like W=mgh=281.5x9.81x0.171 J I have heard that the work done later on by his dentist to fix his dentures was quite hard

11. lgbasallote

a follow up question was (b) What total force was exerted on arfeuille's teeth during the lift what does that mean?

12. CarlosGP

The forced exerted was exactly F=mg=281.5 x 9.81 Newtons

13. rajathsbhat

It means that a downward force equal to the weight he lifted will be exerted on his teeth (the contact point).

14. rajathsbhat

Btw, @CarlosGP, I saw a man on TV lift a 1000kgs (a ton) with his teeth. Jus sayin.

15. CarlosGP

I saw another one make the Statue of Liberty disappear! ;) Can you believe it?

16. rajathsbhat

but this was for real. It was on 'Superhuman' on the DISCOVERY CHANNEL!

17. CarlosGP

I have to see under which conditions was the test carried out. I am not too sure neck muscles can stand that force

18. rajathsbhat

I'll try to find a video..

19. CarlosGP

@rajathsbhat, I would appreciate it! Thanks!

20. lgbasallote

so for (b) it's just gravitational force?

21. lgbasallote

@rajathsbhat

22. rajathsbhat

yes. Sorry, I was busy searching for that vid.

23. lgbasallote

haha lol...

24. rajathsbhat

and yes, it is the gravitational force.

25. lgbasallote

thanks!!`

26. rajathsbhat

yw.