A ball of mass 'm' is moving with initial velocity 4 i ^ m / sec . It strikes a fixed incline plane such that angle of incidence of the ball with normal = angle of reflection of ball with no

Question

A ball of mass 'm' is moving with initial velocity $4 \hat{i} m / sec$ . It strikes a fixed incline plane such that angle of incidence of the ball with normal = angle of reflection of ball with normal. Velocity vector of ball just after collision will be :- (No friction is present between surfaces of ball and wedge)

TestHub · Accepted Answer

Surface tangent t ^ = ( cos 3 0 ∘ , sin 3 0 ∘ ) , normal n ^ = ( − sin 3 0 ∘ , cos 3 0 ∘ ) . v t ​ = v ⋅ t ^ = 4 cos 3 0 ∘ = 2 3 ​ , v n ​ = v ⋅ n ^ = − 2 . Reflection flips the normal component: v ′ = v t ​ t ^ − v n ​ n ^ = ( 3 , 3 ​ ) + ( − 1 , 3 ​ ) = ( 2 , 2 3 ​ ) = 2 ( i ^ + 3 ​ j ^ ​ ) m/s. Answer: (C)

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