A projectile is fired from the ground such that its initial angle of projection is 60^ with the horizontal. At a certain instant during its flight, its velocity vector is observed to be v = (10 i + 10 j ) m/s , where i and j are unit vectors along the horizontal and vertical directions respectively. If air resistance is negligible, the initial speed of the projectile is

Step-by-step solution

In projectile motion, the horizontal component of velocity remains constant throughout the flight. From the given velocity vector v = 10 i + 10 j , the horizontal component of velocity is v_x = 10 m/s . Let the initial speed of the projectile be u . Since the initial angle of projection is 60^ , the initial horizontal component of velocity is: u_x = u 60^ = u 2 Equating the horizontal components: u 2 = 10 u = 20 m/s Answer: 20 m/s