A block of mass 5kg is moving horizontally on a smooth surface in a straight line at 6m/s. In order to change its speed to 10m/s , the work done would need to be .
A 40J
B 90J
C 160J
D 400J
E 550J
please answer with explanation ^^
F.4 physics - mechanics 10 points
2008-08-30 4:26 am
回答 (1)
2008-08-30 4:31 am
✔ 最佳答案
the origrinal kinetic energy of the 5kg block= 1/2 mv^2
=1/2(5)(6)^2
=90J
when the block is moving with 10m/s
its kinetic energy
=1/2 mv^2
1/2(5)(10)^2
=250J
Work done required
=250 - 90
=160J
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