試題詳解

58. As shown in Figure (b) below, a point-like ball with initial velocity v₀ is inclined at an angle of Ψ on the inclined plane and the inclined plane itself is inclined at an angle of Φ.

We know that the distance from the point of launch to the point at which the ball strikes the incline, measured along the incline without taking into account air resistance, is

 Therefore, as shown in Figure (b), what value of θ₀ will maximise R when thrown from a projector with a height h = 2.22 m above the ground and an initial velocity v₀ = 14.0 m/s? (Hint: Solve a quadratic equation of sing and, then, take an approximation: sin6° ≈ 1/10.)
(A) smaller than 40°
(B) about 42°
(C) 45°, exactly
(D) about 47°
(E) larger than 50°