3.3 - Fluid Mechanics And Projectile Motion

Question 1

What 2 factors affect motion?

Answer 1

Drag
Air resistance

Question 2

What is air resistance?

Answer 2

Force that opposes the direction of motion of a body through the air

Question 3

What is drag?

Answer 3

The force that opposes the direction of motion of a body through water

Question 4

What are the 4 factors that affect the magnitude of air resistance and drag on a body?

Answer 4

Velocity
Frontal cross-sectional area
Stream-lining and shape
Surface

Question 5

What is aerofoil?

Answer 5

A streamlined shape with a curved upper surface and flat lower surface designed to give an additional lift force to a body

Question 6

What are the 4 factors which affect projectile release?

Answer 6

Speed of release
Angle of release
Height of release
Aerodynamic factors

Question 7

How does speed of release effect a projectile?

Answer 7

Due to newtons 2nd law - greater the force applied to the projectile, the greater the change in momentum

Question 8

How does angle of release effect a projectile?

Answer 8

90 degrees projectile will go vertically up and come down
45 degrees optimal angle maximise horizontal distance
>45 degrees projectile reaches peak height too quickly and rapidly returns to the ground
<45 degrees projectile doesn’t achieve sufficient height to maximise flight time

Question 9

How does the height of release effect the projectile motion?

Answer 9

If height of release is higher or lower than the landing height the optimal angle will change

Question 10

What is a parabola?

Answer 10

A uniform curve symmetrical about its highest point

Question 11

How would a parabolic flight path occur?

Answer 11

If the weight is dominant and air resistance is very small

Has a symetrical shape about its highest point

Question 12

How would a non-parabolic flight path occur?

Answer 12

If air resistance is the dominant force and weight is very small

Asymmetrical shape

Question 13

What it the Bernoulli principle?

Answer 13

Creation of additional lift force on a projectile in flight

(Higher the velocity of air flow, the lower the surrounding pressure)

Question 14

What is lift force?

Answer 14

Additional force created by a pressure gradient

Question 15

Explain how a ski jumpier would use bernoullis principle? (5)

Answer 15

Ski jumper adopts aerofoil shape
This creates an angle of attack
Air travels further over the top of the ski jumper
Lower pressure above the ski jumper or creates a pressure gradient
Air moves from area of high to low pressure
Lift force created

Question 16

What is downward lift force?

Answer 16

If the aerofoil shape is inverted

Question 17

What is the Magnus effect ?

Answer 17

Creation of additional Magnus force on a spinning projectile which deviated from the flight path

Question 18

What is Magnus force?

Answer 18

A force created from a pressure gradient on opposing surfaces of a spinning body moving through the air

Question 19

What are the 4 types of spin?

Answer 19

Topspin - eccentric force applied ABOVE Centre of mass
Backspin - eccentric force applied BELOW centre of mass
Sidespin (hook) - eccentric force applied to the RIGHT of the centre of mass
Sidespin (slice) - eccentric force applied to the LEFT of the centre of mass

Question 20

What is created due to topspin rotation?

Answer 20

Creates a downward Magnus force, shortening the flight path

Question 21

What is created due to backspin rotation?

Answer 21

Creates an upward Magnus force, lengthening the flight path

Question 22

What is created due to sidespin?

Answer 22

Creates a Magnus force to either the left or right

Causes the projectile to go either right or left

Question 23

How is additional Magnus force created for a ball with topspin?

Answer 23

Upper surface rotates towards air flow, decreasing velocity of airflow and creates a zone of low pressure
The lower surface rotates in the same direction as the airflow, increases velocity and creates a zone of low pressure
A pressure gradient is formed and an additional Magnus force is created downwards