Projectile motion

When an object is thrown or launched with a horizontal velocity, it follows a curved path called a projectile.

This is because of two properties:

• The horizontal velocity stays constant (ignoring air resistance)
• The vertical velocity increases proportionally with time, due to the acceleration of gravity

Solving projectile motion problems

We can use the equations of motion to solve projectile motion problems, by treating the horizontal and vertical components of the motion separately.

For example, if we know the initial velocity of a projectile and the angle at which it was launched, we can calculate the horizontal and vertical components of the velocity using trigonometry.

Then, we can use the normal equations of motion to calculate the time of flight, the maximum height, and the horizontal range of the projectile.

Types of projectiles

Depending on which way the projectille is launched, we can categorise it:

• Horizontally launched projectiles - launched with an initial horizontal velocity and no initial vertical velocity. Basically, fully to the left/right.
• Vertically launched projectiles - launched with an initial vertical velocity and no initial horizontal velocity. Fully up.
• Obliquely launched projectiles - launched with both an initial horizontal velocity and an initial vertical velocity (launched at an angle).

Air resistance

We have to ignore air resistance when solving projectile motion problems, because it would make the calculations much more complicated.