Biomechanics - fluid mechanics and projectile motion

Question 1

What is air resistance

Answer 1

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

Question 2

Define drag

Answer 2

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

Question 3

What factors affect air resistance and and drag

Answer 3

Velocity - greater the velocity, greater the resistance

Frontal cross sectional area - larger the cross sectional are, larger the resistance

Streamline and shape - more streamline and aerodynamic the body is, the lower the resistance

Smooth surfaces

Question 4

Define projectile motion

Answer 4

Movement of a body through the air following a curved flight path under the force of gravity

Question 5

Define projectile

Answer 5

A body that is launched into the air losing contact with the ground surface such as discus

Question 6

The horizontal distance is affected by four factors which are…….

Answer 6

speed
angle
height
aerodynamic

Question 7

Define parabolic flight path

Answer 7

Weight is the dominant force and air resistance is small a parabolic flight path occurs. Which has a parabolic shape symmetrical about its highest point.

Question 8

Define non parabolic flight path

Answer 8

Air resistance is the dominant force and weight is small. so the flight path is non parabolic shape unequal about its highest point.

Question 9

What is a body free diagram

Answer 9

A clearly labelled sketch of a body showing all the forces.

AR - W

Question 10

Explain what the Bernoulli principle is.

Answer 10

Bernoulli shows the creation of an additional lift force on a projectile in flight resulting the conclusion that the higher velocity of air flow, the lower the surrounding pressure.
extending the flight path (discus)

Question 11

Define lift force

Answer 11

Additional force created by a pressure gradient forming on opposing forces of an aerofoil moving through a fluid

Question 12

Define angle of attack

Answer 12

The most favourable angle of release to optimise a lift force due to bernoulli.

Question 13

Define downward lift force

Answer 13

Aerofoil shape is inverted, creating a downward force in Bernoulli lift force. Used in formula 1

Question 14

Define Magnus force

Answer 14

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

Question 15

Define Magnus force

Answer 15

A force created forms a pressure gradient on opposing surfaces of a spinning body.

Question 16

Explain the four types of spin

Answer 16

Topspin - eccentric force applied above centre of mass (spins downwards)

Backspin - eccentric force applied below centre of mass (spins upwards)

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