fluid mechanics

Question 1

fluid mechanics

Answer 1

object travelling through liquid or gas

Question 2

drag force

Answer 2

a force that acts in opposition to motion and has negative effect on velocity (slows something down)
(fluid)

Question 3

what is a drag force produced by

Answer 3

air resistance and friction

Question 4

2 types of drag

Answer 4

1. surface drag

2. form drag

Question 5

surface drag

Answer 5

friction between the surface of an object and the fluid environment

Question 6

form drag

Answer 6

impact of the fluid environment on an object

• The forces affecting the leading edge of an object increases form drag and the forces affecting trailing edge reduces form drag
• relates to streamlining and slipstream

Question 7

streamlining

Answer 7

involving shaping a body so it can move as effectively and quickly through a liquid as possible

Question 8

factors that reduce and increase drag (same as air resistance)

Answer 8

• velocity of moving body = greater the velocity the greater the drag
• cross sectional area = greater the CSA the greater the drag e.g. cyclists lean over handlebars
• shape and surface characteristics = clothing with ridges and aerodynamic helmets

Question 9

the bernoulli principle

Answer 9

when air molecules exert less pressure the faster they travel and more pressure when slower

Question 10

lift force

Answer 10

causes a body to move perpendicular to the direction of travel (allows discus to stay in the air for longer increasing the horizontal distance)

Question 11

angle of attack

Answer 11

the tilt of a projectile relative to the air flow

Question 12

how is lift achieved?

Answer 12

when different air pressures act on an object

Question 13

optimum angle of attack for discus

Answer 13

25-40 degrees

Question 14

explain movement of a discus

Answer 14

AOA changes flow of air around discus so air on top has longer distance than below. Air above travels at a faster velocity which creates lower pressure causing an upward lift force. If AOA is too great then lift is reduced and drag increases
- air tries to move from high to low pressure causing a lift force

Question 15

explain movement of formula 1 sports cars

Answer 15

spoiler is angled so the lift force can act in a downward direction to push the car into the track. Air that travels above has a shorter distance than below due to the angle of the spoiler. Air above travels at a slower velocity at a higher pressure which creates a greater frictional force so tyres grip onto track

Question 16

movement of cyclists

Answer 16

low streamlined position means that air travels a shorter distance above and longer below. Air above travels at a slower velocity at a higher pressure which creates a greater frictional force so tyres grip onto track

Question 17

movement of speed skiers

Answer 17

need to stay in contact with the ice for faster speed because more downward acting lift means more force which melts the snow for friction free surface