A projectile is fired from the origin. At x = 20 m, its velocity makes an angle 45° below the horizontal. At the same point, the horizontal component of velocity is 10 m/s. If the projectile was initially projected upward, its initial vertical component of velocity was: (Take g = 10 m/s²)
Options

Question

A projectile is fired from the origin. At x = 20 m, its velocity makes an angle 45° below the horizontal. At the same point, the horizontal component of velocity is 10 m/s. If the projectile was initially projected upward, its initial vertical component of velocity was: (Take g = 10 m/s²)

Options

G1 Physics · Accepted Answer

Horizontal velocity remains constant, so vₓ = 10 m/s. Time to reach x = 20 m is t = x/vₓ = 20/10 = 2 s. Since the velocity is 45° below horizontal, vᵧ = -10 m/s. Using vᵧ = uᵧ - gt: -10 = uᵧ - 10(2), hence uᵧ = 10 m/s. Therefore option B is correct.