Fluid mechanics Flashcards
define drag force
force that acts on a body travelling through water
define air resistance
force that acts on a body travelling at high velocity through the air
describe how air resistance and drag force affects performance
they act against motion of a body of a body & place increased physiological demand, which can lead to early fatigue and poor performance
state the factors that reduce and increase drag
- velocity of moving body
- cross-sectional area of the moving body
- streamlining and shape
- surface characteristics of a moving body
- mass of performer
explain the factors that reduce and increase drag/ air resistance and give a sporting example for each
- velocity of moving body: the greater the velocity of a body moving through a fluid, the greater the drag force OR the greater the velocity of the body, the greater the air resistance. e.g. a racing car, cyclists or sprinter wil experience greater air resistance in their competition, which increases drag.
- the cross-sectional area of the moving body: the larger the cross-sectional area of the body, the greater the drag/ air resistance e.g. in cycling, the cyclists reduce cross-sectional area by crouching low over the handlebars rather than sitting upright
- streamlining and shape: the more streamlined and aerodynamic the shape of the moving body, the lower the drag e.g. speed skiers wear helmets that extend to their shoulders to give a more streamlined shape
- surface characteristics of a moving body: the smoother the surface the lower the air reisstance/ drag e.g. lycra worn in cycling for more streamlined shape
- mass of performer: the greater the mass the less its motion is changed by air resistance or drag e.g. bodies with a smaller mass slow down quickly due to fluid friction. air resistance can decrease due to reduced velocity
explain the factors affecting the horizontal displacement of a projectile
- height of release: a greater release height results in greater horizontal displacement e.g. force of gravity is constantly acting on the mass of the shot put so shot putter should try to release the shot at the highest point possible
- **angle of release: ** when the release height and landing height are equal then optimum angle of release is 45 degrees e.g. long jumper. if release height is below landing height then optimum angle needs to be greater than 45 degrees e.g. shooting in basketball. if release height is greater than the landing height the optimum andle of release needs to be less than 45 degrees e.g. shot put
- speed of release: the greater the release velocity of a projectile the greater the horizontal displacement travelled e.g. velocity that the shot leaves the hand will affect the horizontal displacement
describe the factor affecting paths of different projectiles
- weight and air resistance are 2 forces that affect projectiles in the air ( these 2 factors are crucial ind eciding whether a projectile has a flight path that is parabolic or non-parabolic)
- parabola (symmetrical) : in projectiles with a larger mass (shot put) the weight arrow is larger than air resistance as gravity is the greater force acting on the flight path. air resiatance is negligable
- non-parabolic: in projectiles with a lighter mass (badminton shuttle) the air resistance is the greater force affectung its path e.g. intially the shuttle starts off with a high velocity due to force form the racket but as the shuttle continues its flight path the air resistance reduces its velocity
draw a parabolic flight path
shot put is parabolic
draw a non-parabolic flight path
draw a free body diagram of a shuttle cock
draw a free body diagram of a shot put
draw a resultant force diagram for a shotput
draw a resultant force diagram for a shuttlecock
