400882 Introduction to Biomechanics - Projectile Motion

Any object thrown into the air is known as what?

A Projectile

The flight pathway of a projected object is referred to as the what?

The trajectory

During human projectile motion, which body location is generally used for analysis?

Centre of Mass (COG or COM)

In true projectile motion (objects in freefall), which two external forces act on the projectile?

Gravity & Air Resistance

During projectile motion, which flight component does gravity affect?

The vertical component

• a (acceleration) due to gravity = -9.8m/s² (-ve because of the direction of travel)

• Affects the height (vertical) travelled

During projectile motion, which flight component does air resistance affect?

The horizontal component

• Affects the distance travelled

When ignoring air resistance, what affect does the size shape and mass of an object have on the acceleration of that object due to gravity?

It has no effect on acceleration due to gravity

The flight path of a projectile that is not influenced by air resistance would follow a trajectory of which shape?

A parabola - perfectly mirrored on both sides of the apex

A projectile at the apex of its flight is represented by a vertical velocity of?

At the apex of flight its Vv (vertical velocity) is 0

For a projectile that is released from and lands at the same height (ignoring air resistance), the time taken for that projectile to reach the apex of its flight is equal to what percentage of the total flight time?

Exactly half.

List three release factors that affect the trajectory of a projectile.

• Angle of projection Relative angle of release)

• Speed of projection (relative speed of release)

• Height of projection (relative height of release)

Define Projection Angle.

The angle at which a body is projected with respect to the horizontal

- Influences the shape of the objects trajectory

• Vertical (straight up and down)

• Parabola (full parabolic curve)

• Horizontal (half parabola)

52. In the absence of air resistance, a projectile that is launched from a height of 2.5 m with a projection angle of 0° will produce a flight trajectory of which shape?

Half parabola

Define Projection Speed and state which components of a projectiles trajectory that it can influence.

Projection speed is the magnitude of projection velocity and influences

• Height of trajectory

• Horizontal length of trajectory

What is meant by the relative height of release (Height of Projection)?

The difference between the height at which the projectile is released and the height at which it lands.

What effect does increasing the height of projection have on a projectile?

Increased projection height →increased time of flight → increased range (horizontal distance)

How can maximum range / distance be achieved in projectile motion?

By maximizing:

• Speed of projection and

• Release height

Describe how the optimum release angle for a projectile changes depending on whether the release height is: greater than; equal to; or less than the landing height.

• When release height is zero then optimal release angle is 45°

• Release height above zero = optimal release angle <45°

• Release height below zero = optimal release angle >45°

Under what condition can the equations for uniformly accelerated motion be applied?

Where 2 quantities are known and we have to solve for a third