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Motion In A Plane

Question
CBSEENPH11026392

A projectile is given an initial velocity of i^ + 2 j^ The cartesian equation of its path is ( Take g= 10 ms2 )

  • y = x - 5x2

  • y = 2x - 5x2

  • y = 2x - 15 x2

  • y = 2x - 25x2

Solution

B.

y = 2x - 5x2

Given:-

The initial velocity of a projectile is given by

    u = i^ + 2 j^

        = ux i^ + uy j^

Then,

   ux = 1 = u cosθ

    uy = 2 = u sinθ

∴       tanθ = u sinθu cosθ

                 = 21

        tanθ = 2

The equation of trajectory of a projectile motion is

   y = x tanθ -  g x22 u2 cos2θ

       = x tanθ -  g x22 u cosθ 2

∴  y =  (x × 2 ) -  10 × x22 12

   y = 2x - 5x2