Question

Mass of m kg is suspended by a weightless string. the horizontal force that is require to displace until the string makes an angle of 450 with the initial vertical direction is

Answer 1

Explanation:

The work done by the force will be equal to the potentail energy gained by the mass.

Let L be the length of the string ,

F.d= MgL (1 -cos45 )

The horizontal displacement of the mass is d= L sin 45

F L sin45 = Mg L(1 - 45)

F = Mg (sq. root 2 - 1)

USE CONSERVATION OF ENERGY

Let x be the force required

T Sin 45=M kg …....1

T Cos45=x ….......2

Divide equation 1 and 2,

1=M/x

x=M