Question

a boy is pulling a cart by supplying a constant force of 8N on a straight path of 20 m.On around about of 10 m diameter he forgets the past and takes 1and1/2 turns and then continues on a straight path for another 20 m.Find the net work done by the boy on the cart

Answer 1

Net work done = 440 J

Answer 2

Work done in covering 20m with a constant force of 8n  

W=Fs  

=> W1 = 20 x 8 =160 J  

Now distance covered in coverung one and half circle of diameter 10m will be  

Diameter = 10m

Radius = 5  

Distance covere in 1 full circle  

Circumfrance = 2πr  

=2x22/7x5

Distance covered in one and half circle  

=πr

=227x5  

Totaldistance coverd in one and half circle  

=2x22/7x5+22/7x5

=47.14

=47 approx  

Now work done will be  

W2=8x47=376J

Travelling again fo 20m work dine will be  

W3=20x8=160J  

total work done  

=W1+W2+W3

W=160+376+160

696J