A particle is projected in the X-Y plane. 2 s after projection, the velocity of the particle makes an angle 45 ° with the X-axis. 4 s after projection, it moves horizontally. Find the velocity of projection (use g = 10 m s - 2 )

Question

A particle is projected in the X-Y plane. 2 s after projection, the velocity of the particle makes an angle 45 ° with the X-axis. 4 s after projection, it moves horizontally. Find the velocity of projection (use g = 10 m s - 2 ), 20 5 m s - 1, 10 5 m s - 1, 5 5 m s - 1, 2 5 m s - 1

MARKS App · Accepted Answer

v y = u y + a y t at the highest point of motion, v y = 0 0 = u y - gt u y = 4 g = 40 m s - 1 at t = 2 s v y = u y + a y t v y = 4 g - gt = 20 m s - 1 given that v y = u x = 20 m s - 1 the velocity of projection u = u x 2 + u y 2 ⇒ u = 40 2 + 20 2 u = 2000 ⇒ 20 5 m s - 1

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