Projectile Motion — Flashcards & Quiz

Q1: What are the two key principles of projectile motion?

1) Horizontal and vertical motions are independent. 2) Horizontal velocity is constant (no horizontal acceleration); vertical motion has constant acceleration (g = 9.8 m s⁻² downward). Treat the two components separately, then combine to find trajectory.

Q2: What equations govern the horizontal and vertical motion of a projectile?

Horizontal: x = v_x t (constant velocity). Vertical: v_y = u_y − gt, y = u_y t − ½gt², v_y² = u_y² − 2gy (constant acceleration −g). Combine equations to find range, maximum height, and time of flight.

Q3: What is the trajectory shape of a projectile and what is the range formula?

The trajectory is a parabola (assuming no air resistance). For launch and landing at the same height, range R = (v₀² sin 2θ)/g. Maximum range occurs at θ = 45°. Time of flight: t = (2v₀ sin θ)/g.

Q4: How does air resistance affect projectile motion?

Air resistance opposes motion, reducing both horizontal and vertical components of velocity. The trajectory is no longer symmetric — range is reduced, maximum height is reduced, time of flight is reduced, and the descent is steeper than the ascent. Terminal velocity may be reached.

Q5: What are the horizontal and vertical velocity components at the peak of a projectile's flight?

At maximum height, the vertical velocity component is zero (v_y = 0) while the horizontal component remains constant (v_x = v₀ cos θ). The projectile momentarily stops moving vertically but continues moving horizontally.

Q1: Horizontal and vertical motions of a projectile are independent of each other.

Answer: TRUE

Horizontal motion (constant velocity) and vertical motion (constant acceleration −g) can be analysed separately and do not affect each other.

Q2: A projectile launched horizontally has zero initial vertical velocity.

Answer: TRUE

When launched horizontally, u_y = 0. Vertical velocity increases due to gravity as the projectile falls.

Q3: The maximum range for a projectile is achieved at a launch angle of 60°.

Answer: FALSE

Maximum range (for launch and landing at the same height) occurs at θ = 45°, not 60°. R = (v₀² sin 2θ)/g is maximum when sin 2θ = 1.