Question

The bob of simple pendulum is held in the horizantal position calculate the speed of the bob of pendulum at the lowest position B when released and the length of pendulum is 0.5 meter and assume that there is no loss of energy ​

Answer 1

Answer:

Increase in potential Energy of bob

=

m

g

Δ

h

where

m

is mass of bob,

g

=

9.81

m

s

−

2

is acceleration due to gravity and

Δ

h

is change in height of bob.

As shown in the figure,

Δ

h

=

L

−

L

cos

θ

. Inserting given values we get

Work done on the bob

=

0.5

×

9.81

(

20

−

20

cos

30

∘

)

⇒

Work done on the bob

=

0.5

×

9.81

×

20

(

1

−

√

3

2

)

=

13.1

J