Horizontal and Vertical Components of Projectile Motion
A body is pro...
Question
A body is projected with a velocity of 30 m/s at an angle of 60∘ to the horizontal. Find the magnitude of velocity when the angle between the velocity vector and acceleration vector is 120∘.
A
20√3 m/s
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B
20√3 m/s
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C
10√3 m/s
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D
10√3 m/s
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Solution
The correct option is C10√3 m/s Let the final velocity be V when the angle between velocity vector and acceleration vector is 120∘. Only acceleration acting on the body will be acceleration due to gravity in downward direction as shown in figure.
Hence angle made by velocity vector with horizontal, ϕ=120∘−90∘=30∘ Since there is no acceleration in horizontal direction, therefore horizontal velocity remains same during the projectile. ∴uxcos60∘=Vcosϕ 30cos60∘=Vcos30∘ 15=V×√32 ⇒V=10√3 m/s