ICSE Class 10 Physics 2020 Solved Paper

SECTION - II

The figure below shows a simple pendulum of mass $200 {\g}$ . It is displaced from the mean position A to the extreme position B. The potential energy at the position $A$ is zero. At the position $B$ the pendulum bob is raised by $5 {\m}$ .

Question : 29 of 67

Marks: +1, -0

What is the speed of the bob at the position

A

when released from

B

?
(Take

{\g}=10 {\ms}^{-2}

and there is no loss of energy.)

Solution:

Let the speed of the bob at position

A

be '

v

'.
Total mechanical energy at A

=

Total mechanical energy at

B

\;{1}/{2} m v^2+0\;=10

\;{1}/{2} × \;{200}/{1000} × v^2\;=10

v^2\;=\;{2000 × 10}/{200}

v^2=100, ∵ v={√{100}}=10 {\m} \/ {\ s}

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