physics work done

I suppose we also need to take into account the weight of the block in the calculation of work done, as the block is moving upward.

Net force = (50 - 3 - 2g) N = 27 N
where g is the acceleration due to gravity, taken to be 10 m/s^2
Hence, work done = 27 x 3 J = 81 J

2013-10-20 11:09:58 補充：
但圖上是顯示50 N的，而且題目是說物體向上移動，那麼題目文字上的5N很可能是打錯了。
希望發問者能給予澄清。

Thanks May~

☆ヾ(◕‿◕)ノ

2013-10-20 01:18:51 補充：
天同，我同意要計埋個weight，但根據題目個 force 應該係 5N，唔係50N？

2013-10-20 01:26:12 補充：
但若 net force 向下，則不應向上行走．．．

奇怪．．．

2013-10-29 20:38:39 補充：
他已經消失得無影無蹤～

似乎都要投票～

當然我必定投你～

^__^

woooo.....excellent ye!!!