Question

Two wires of brass are under load of 50 N
each. If the ratio of their lengths are 2 : 3 and
their cross section area is 4 : 7, then the ratio
of their extension is

Answer 1

Answer:

Correct option is

A

1:2

Given,

l

1

:l

2

=1:2

r

1

:r

2

=1:2

Δl

1

=Δl

2

Area, A=πr

2

A∝r

2

A

1

:A

2

=1:4

The material are same, so the modulus is also equal,

Y

1

=Y

2

Δl/l

1

F

1

/A

1

=

Δl/l

2

F

2

/A

1

F

2

F

1

=

l

1

l

2

.

A

2

A

1

F

2

F

1

=

1

2

×

4

1

=

2

1

F

1

:F

2

=1:2

The correct option is A.