A pile driver of mass 1000 kg, hits a post 3 m below it. It moves the post 10 mm. Assuming gravity = 10 m/s, what is the kinetic energy of the pile driver?
- 30 kJ.
- 45 kJ.
- 90 kJ.
Explanation from PART66Online
Falling 3 m, the pile driver converts its potential energy into kinetic energy: KE = mgh = 1000 x 10 x 3 = 30,000 J = 30 kJ at impact. The 10 mm the post moves relates to the impact force, not the kinetic energy on arrival.
R
ranz130 asked · 18 Aug 2013
still not get it,can somebody explain it.
Community Comments (4)
B
binoybose11
20 Aug 2013
i think its like this KE=PE
therefore 1/2mv2=mgh
mv2=2mgh
v2=gh
v2=10*3
v2=60
now, ke=1/2mv2
ke=1/2 1000*60
=1000*30
=30,000J
=30KJ
therefore 1/2mv2=mgh
mv2=2mgh
v2=gh
v2=10*3
v2=60
now, ke=1/2mv2
ke=1/2 1000*60
=1000*30
=30,000J
=30KJ
R
ranz130
20 Aug 2013
thanks..
J
Jacktrigg
24 Aug 2013
I think it wants you to calculate the potential
M
minnesota
20 Dec 2015
tnx
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