Question

3(a). A projectile is fired at an angle, θ, to the horizontal with velocity, u. Show that at any time, t, during the motion: (i) the horizontal component of the velocity is independent of t; (ii) the vertical component of the velocity depends on t.
3(b). State the assumption on which projectile motion is based.

Accepted Answer

(a)(i) Horizontal component: vₓ=uₓ-gt sin0=uₓ (since gₓ=0, there is no horizontal acceleration), so vₓ=uₓ=u cosθ, which is independent of t.
(ii) Vertical component: v_y=u_y-gt=u sinθ-gt, which clearly depends on t.
(b) Assumption: the only force acting on the body is its weight/force of gravity — all other external forces (e.g. air resistance) are negligible.

WAEC Physics 2023 Theory — Question 3

Sign up free to unlock