An inclined plane makes an angle 30° above the horizontal. A projectile fired from a point on the plane at 45° with the horizontal has a certain range along the plane. Another angle of projection with the horizontal that gives the same range is:
Options

Question

An inclined plane makes an angle 30° above the horizontal. A projectile fired from a point on the plane at 45° with the horizontal has a certain range along the plane. Another angle of projection with the horizontal that gives the same range is:

Options

G1 Physics · Accepted Answer

For two projection angles θ₁ and θ₂ giving the same range on an inclined plane of angle α, θ₁ + θ₂ = 90° + α. Here α = 30° and θ₁ = 45°. Therefore θ₂ = 90° + 30° - 45° = 75°. Hence option B is correct.