Effects of Air Resistance

What is Air Resistance?

A resistive force that opposes motion; an example of drag force.

What factors does Air Resistance depend on? (Factors affecting Air Resistance)

Shape of the body, speed of the body, viscosity of the fluid.

How does Air Resistance affect horizontal motion?

It acts as the net force, causing velocity to decrease. Acceleration is initially maximum, then decreases in magnitude as speed falls. Speed eventually becomes zero.

How does Air Resistance affect vertical motion (Moving Upwards)?

Air resistance acts downwards (in same direction as weight) -> net acceleration downwards is > g -> speed decreases rapidly. Air resistance decreases as speed decreases -> net acceleration also decreases.

What is the net acceleration at maximum height (moving upwards with air resistance)?

Equal to g, as the body is momentarily at rest and air resistance is zero.

How does Air Resistance affect vertical motion (Moving Downwards)?

Air resistance acts upwards (opposing weight) -> net acceleration downwards is < g -> speed increases at a decreasing rate. Air resistance increases as speed increases -> net acceleration decreases.

What is Terminal Velocity?

The constant velocity achieved when air resistance equals the magnitude of the body's weight, resulting in zero net force and zero net acceleration.

What happens to Kinetic Energy at Terminal Velocity?

Remains constant. Decrease in GPE is totally converted to thermal energy (dissipated to surroundings).

How does Air Resistance affect the Trajectory of Projectile Motion?

Trajectory is no longer symmetrical. Horizontal velocity is not constant (decreases), and range is smaller. Vertical acceleration is more than g on the way up, and maximum height is smaller.

What is the consequence of air resistance on height and range?

The trajectory reaches a shorter height and ends with a shorter range. It is also asymmetrical.

Topic: Appendix (Proof of Parabolic Path of a Projectile)

What is the significance of the mathematical expression for vertical vs. horizontal displacement?

It shows a quadratic relationship between vertical (sy) and horizontal (sx) displacement, proving the trajectory is a parabola (assuming negligible air resistance).