Kinematics

JEE Main level, single correct, medium

288 of 308

Question 288 of 308

A child of mass 5kg5kg is going round a merry-go-round that makes 11 rotation in 3.14s3.14s. The radius of the merry-go-round is 2m2m. The centrifugal force on the child will be

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Answer: (B) 40N40N

The angular speed (ω)\left(\omega \right) of the child can be calculated as follows:
ω=2π3.14=2rads−1\begin{matrix}\omega & = & \dfrac{2\pi }{3.14} \\ & = & 2rad{s}^{-1}\end{matrix}
The formula to calculate the centrifugal force on the child is given by
Fr=mω2r...(1){F}_{r}=m{\omega }^{2}r...(1)
Substitute the values of the known parameters into equation (1) to calculate the required centrifugal force.
Fr=5kg×(2rads−1)2×2m=40N\begin{matrix}{F}_{r} & = & 5kg\times {\left(2rad{s}^{-1}\right)}^{2}\times 2m \\ & = & 40N\end{matrix}

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