Question

A spring is stretched by 5 cm. Its potential energy is E. If it is stretched by 10 cm, its potential energy
will be:
2017-01 Eng
A) 2
B) 4E
C) 8E
D)16E

​

Answer 1

answer is 4E...........

Answer 2

A long spring is stretched by 2cm and its potential energy is U. If the spring is stretched by 10cm; its potential energy will be (in terms of U)

MEDIUM

Help best friend

Study later

ANSWER

The potential energy of a stretched spring is

U=

2

1

kx

2

Here, k= spring constant,

x= elongation in spring.

But given that, the elongation is 2cm.

So, U=

2

1

k(2)

2

⇒U=

2

1

k×4 ......(i)

If elongation is 10cm then potential energy

U

′

=

2

1

k(10)

2

U

′

=

2

1

k×100 ......(ii)

On dividing equation (ii) by equation (i), we have

U

U

′

=

2

1

k×4

2

1

k×100

or

U

U

′

=25⇒U

′

=25U