Question

A mass M kg is suspended by a weightless
string. The horizontal force required to hold
the mass at 60° with the vertical is
1) Mg
2) Mg root 3
3) Mg(root3+1)
4)Mg / root 3

Pls tell the correct answer

Answer 1

Work done by tension + Work done by force (applied) + Work done by gravitational force = change in kinetic energy

Work done by tension is zero

⇒0+F×AB−Mg×AC=0

⇒F=Mg(ACAB)=Mg⎡⎣⎢1−12√12√⎤⎦⎥

[∵AB=lsin45∘=l2–√

and AC=OC−OA=l−lcos45∘=l(1−12–√)

where l= length of the string.]

F⇒Mg(2–√−1)

Answer 2

Answer:

answer is option 2) Mg root 3