NEET Exam Model Paper 7

The steel wire is first stretched by an object of specific gravity ρ in air. Then the object is half
submerged in water. The stretching force diminishes due to upthrust of water on the object. Let σ denote specific gravity of water. Weight of the object =Vρg
Upthrust of water on object =

V

2

σg
∴ Tension T′=Vρg−

Vσg

2

or T′=Vg(

2ρ−σ

2

)
υ=

1

2l

− T

µ

where T=Vρg
υ′=

1

2l

− T

µ

‌‌‌‌‌∴

υ′

υ

=

− T ′

T

or

υ′

υ

=

––––––––––––––––––––––––

Vg(2ρ−1) 2 × 1 Vgρ

or υ′=υ√

2ρ−1

2ρ

or υ′=300[

2ρ−1

2ρ

]

1

2