Analyse the motion of projectiles by resolving the motion into horizontal and vertical components

• Projectile: Any object launched into the air.
• Trajectory: The path that a projectile follows during its flight.
• In the absence of air resistance, a projectile will trace out the shape of a parabola (below left), although the Earth’s atmosphere causes this shape to be slightly deformed (below right):

• The motion of a projectile can be regarded as two separate and independent motions (horizontal and vertical)
• The two components (horizontal and vertical) together combine to form the projectile motion in 2 dimensions
• Because the two motions are perpendicular, and hence independent, they can be treated and analysed separately.
• The vertical motion of a projectile is accelerated directly down due to gravity at approximately 9.8 ms-2. Thus, it will rise up (due to its vertical component of initial velocity), slow to a halt in the air, and then fall back down to Earth.
• In terms of horizontal motion, a projectile does not undergo acceleration, and thus travels with a uniform velocity (ignoring air resistance).
• It is the combination of uniform vertical downward acceleration and uniform horizontal velocity that produces the parabolic shape of a projectile’s path of motion.

Extract from Physics Stage 6 Syllabus © 2017 NSW Education Standards Authority (NESA)