The bob of a pendulum of length 2 m lies at P. When it reaches Q it loses 10% of its total energy due to air resistance. For this event, which of the following is a correct statement.

The bob of a pendulum of length 2 m lies at P. When it reaches Q it lo

1.	The bob of a pendulum of length 2 m lies at P. When it reaches Q it loses 10% of its total energy due to air resistance. For this event, which of the following is a correct statement.
Answer» The velocity at Q is `1m//s` The velocity at Q is `6m//s` The acceleration at Q is `3m//s^(2)` The acceleration at Q is `6m//s^(2)` SOLUTION :`K.E=(1)/(2)mv^(2),P.E.=mgh` K.E. at Q = 90% of P.E. at P `(1)/(2)mv^(2)=(90)/(100)mgh` `v^(2)=0.9ghxx2` `v=sqrt(1.8gh)` Here `g=10m//s^(2) h=2` `THEREFORE` Velocity at `Q,v=sqrt(1.8xx10xx2)=sqrt(36)=6m//s` The other statements are incorrect.