Posted by kelly on Friday, April 8, 2011 at 11:04pm.
A boy on a bucycle drags a wagon full of newspapers at 0.80m/s for 30 minutes using a force of 40N. How much work has the boy done?

Physics  Jai, Friday, April 8, 2011 at 11:47pm
recall that speed is distance traveled per unit time, or
v = d/t
also recall that work is force exerted times distance, or
W = Fd
since in the problem we are only given the force, we calculate for the distance first.
substituting the given speed and time to formula for speed:
v = d/t
0.8 = d/(30*60)
d = 0.8*30*60 = 1440 m
note: we multiplied 30 by 60 to convert units to seconds.
substituting to get work,
W = Fd
W = 40*1440
W = 57600 J or 57.6 kJ
hope this helps~ :) 
Physics  nianz, Saturday, September 1, 2012 at 4:36am
the answer should be 0J