Projectile Motion
What is projectile?
 A projectile is any object released into
the air. Once an object is in the air its
flight path is governed by factors prior to
its release.
Factors affecting the flight
path of a Projectile are:
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Gravity
Air Resistance
Speed of Release
Angle of Release
Height of Release
Spin
Speed of Release
 This refers to how fast the object is
released (thrown or hit).
 A projectiles speed of release is largely
determined by the muscle force.
 Generally, the greater the speed of
release, the greater the distance gained
Angle of Release
 This refers to the angle that the object is
thrown at or hit into the air
Angle of Release
 In sporting situations the angle of release
varies according to the activity. In
activities such as shooting a basketball
angle above 45 degrees is required. In
activities such as tennis a lower, around 3 to 15 degree angle is required.
Angle of Release
What would happen if the angle of release were too
high for a given activity?
Poor distance gained
What would happen if the angle of release were too
low for a given activity?
Poor flight time and possibly poor distance
Height of Release
 This refers to how high above the
ground an object is released at.
Height of Release
 Increasing the height of release improves
the horizontal distance objects can be
projected.
 For a given speed and angle of release,
the greater the height of release the
greater the distance gained.
 This is because the time in the air will be
greater.
Height of Release
 Would this mean that a golfer hitting a
ball off the top of a hill would hit it further
than a golfer at the bottom of the hill?
Why?
 Yes – the ball will stay in the air longer so
will have a greater chance to fly further.
This assumes the same club and force is
used.
Spin
 When applying force to a projectile below,
above or to the side of the COG you will
impart spin onto the projectile.
 This helps the projectile to maintain its
course and can cause it to change height
or direction.
Spin
 Spin happens as a ball moving through
the air will move in the direction of least
air pressure.
 When you hit the ball you create an area
of high pressure meaning the ball will
travel in the opposite direction to the side
you hit.
Spin continued…
There are 4 main types of spin that can be
imparted to a projectile:
1. Top Spin – this is where you hit over the ball.
Top spin creates a downward force on the ball
causing the ball to drop.
Spin continued…
2. Back Spin – this is where you hit under or slice
the ball.
Backspin creates an upward force that lifts the ball
causing the ball to rise.
Spin continued . . .
3. Clockwise Spin – this is where you hit the
ball on the left side of the COG.
It causes the ball to swing to the Right.
Spin continued . . .
4. Anticlockwise Spin – this is where you hit
the ball on the rightside of the COG.
It causes the ball to swing to the Left.
Gravity
 What is the effect of gravity on a
projectile?
 It decreases the height a projectile can
attain.
Air Resistance
 There are several key factors that bring air
resistance into play:
 The larger the surface area, the more air
resistance will affect the object. E.g a
basketball compared to a golf ball.
 The type of surface of the object. If the surface
is rough then air resistance will be greater.
 Speed. As speed increases, so does air
resistance. E.g a space shuttle (friction)
 Mass. The smaller the mass (lighter the
object), the more air resistance will affect it.