http://sgforums.com/forums/2297/topics/322129 en-US 60 <p>dude cmon. you should be able to solve these problems right away -.-</p> <p>practice makes perfect =]</p> Sun, 29 Jun 2008 13:46:55 +0800 sgforums.com:2297:322129:8204685 -*:+:MUSE:+:*- http://sgforums.com/forums/2297/topics/322129 <p>By the principle of conservation of energy,</p> <p>Loss in PE = Gain in KE</p> <p>mgh = ½mv²</p> <p>(10)(0.8) = ½v²</p> <p>v² = 16</p> <p>v = 4 m/s</p> Wed, 25 Jun 2008 21:06:39 +0800 sgforums.com:2297:322129:8195247 wishboy http://sgforums.com/forums/2297/topics/322129 <p>A 4.0 kg mass of metal is dropped a distance 0.8m onto the horizontal surface in order to test its hardness.</p> <p>&nbsp;</p> <p><strong>What is the velocity of the body just before hitting the horizontal surface?</strong></p> <p>&nbsp;</p> <p>For reference purposes, here are the earlier questions:</p> <p>&nbsp;</p> <p>(a) when the mass has falen through 0.8m, how much gravitational potential energy has been transformed? [g = 10m/s2]</p> <p>Using the mgh formula, you get 32 J</p> <p>&nbsp;</p> <p>(b) How much kinetic energy does the mass possesss before it hits the horizontal surface?</p> <p>I wrote 32 J, similar to the above. Ain't sure what is the velocity so I can't apply the 1/2mv^2 method. I take it that the total energy in the system remains constant - part of the principle of conservation of energy.</p> <p>&nbsp;</p> <p>&nbsp;</p> Wed, 25 Jun 2008 20:54:47 +0800 sgforums.com:2297:322129:8195231 bonkysleuth http://sgforums.com/forums/2297/topics/322129