Question

a boy pulls a toy with a force of 50N through a sting, which makes an angle 30degree with the horizontal so as to move the toy to a distance of 1m horizontally. If the string were inclined making an angle of 45 degree , with the horizontal , how much pull would he apply the string in order to move it in the same distance of 1m

Answer 1

for case 1, work done will be

W = Fscosθ

here,

F = 50N

s = 1m

θ =30 degrees

so,

W = 50*1*cos30

thus,

W = 25√3 J

and

for case 2, work done will be

W = F'scosθ' = 25√3 J

here,

s = 1m

θ' = 45 degrees

so,

F'*1*cos45 = 25√3 J

or

F' = 25√3 / cos45

thus,

F' = 61.2 N