A projectile is launched with initial velocity components uₓ = 20 m/s and uᵧ = 30 m/s. Neglect air resistance and take g = 10 m/s². The time after projection when its velocity makes an angle 45° below the horizontal is:
Options

Question

A projectile is launched with initial velocity components uₓ = 20 m/s and uᵧ = 30 m/s. Neglect air resistance and take g = 10 m/s². The time after projection when its velocity makes an angle 45° below the horizontal is:

Options

G1 Physics · Accepted Answer

Horizontal velocity remains vₓ = 20 m/s. For the velocity to be 45° below horizontal, vᵧ = -20 m/s. Using vᵧ = uᵧ - gt: -20 = 30 - 10t ⇒ t = 5 s. Therefore option C is correct.