A block of mass `m = 1 kg` is released from point `A` along a smooth track as shown. Part `AB` is circular with radius `r_(1) = 4 m` and circular at `C` with radius `r_(2)`. Height of point `A` is `h_(1) = 2m` and of `c` is `h_(2) = 1m (g = 10 m//s^(2))`.
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The force exerted by block on the track at `B` is

Options

A. 10 N
B. 20 N
C. 30 N
D. 40 N

Answer

B

Explanation

`v_(2) = sqrt(2gh_(1)) , N = mg + (mv_(2)^(2))/(r_(1))`.