3- Biomechanics Flashcards
How topspin in tennis causes the flight path to deviate (use airflow)
- UPPER: airflow is in the opposite direction to the spin of the ball
- UPPER: low velocity, high pressure
- LOWER: airflow is in the same direction to the spin of the ball
- LOWER: high velocity, low pressure
- gradient going from high pressure to low pressure
- as a result Magnus force acting downwards
- Flight path shortens and dips (less time in the air)
One benefit of using topspin in tennis
- hit the ball harder and it will still land in the court
- can deceive opponents
How does the speed of release and height of release affect the horizontal distance travelled by a projectile
- faster the speed of release the further the projectile travels
- The higher the release compared to landing the further the projectile travels
two factors affecting the size of the moment of inertia of a rotating body
- mass of the body
- distribution of mass
using a practical example describe the relationship between moment of inertia and angular velocity
Inverse relationship
- Tucked position in gymnastics somersault : low moment of inertia and high angular velocity
- Straight position in gymnastic somersault: high moment of inertia and low angular velocity
Define Angular Momentum
quantity of angular motion possessed by a rotating body
Define moment of inertia and the measurement used
resistance of the body to change its angular motion (kgm^2)
Define Angular velocity
rate of change in angular displacement
Four types of force acting on a cyclist while they pedal forwards
- Weight (Down from COM)
- Reaction (up from both wheels)
- Air resistance (backwards from COM)
- Friction (forwards from ground on both wheels)
Use angular analogue of Newtons 1st law of motion to explain how the skater can increase rate of spin
- skater brings arms or legs in (closer to longitudinal axis)
- reducing moment of inertia
- increasing angular velocity
- principle of conservation of angular momentum
- AM= MI x AV
How a ski jumper can apply Bernoullis principle to maximise the distance travelled
- adopts an aerofoil shape
- create an angle of attack (17 degrees)
- UPPER: air travels further
- UPPER: higher velocity and lower pressure
- LOWER: lower velocity and a higher pressure
- air travels from high to low
- Lift force created
What is the equation and the units for angular velocity
angular displacement / time
rads -1
Explain how a golfer creates a hook shot and the effect on the flight path
- Eccentric force
- causes side spin
- LEFT SIDE: higher velocity and lower pressure
- RIGHT SIDE: lower velocity and higher pressure
- air travels from high to low pressure
- Magnus force
factors other than mass that impact on the air resistance of a ball in flight
- velocity
- shape (more aerodynamic)
- greater frontal cross sectional area
- the smoother the surface
- spin
metric units of measurement for displacement and acceleration
Displacement: metres
Acceleration: m/s squared
Describe linear motion and angular motion
- linear motion : movement of a body in a straight or curved line
- Angular motion : movement of a body in a circular path
factors that affect the size of moment of inertia of the trampolinist during a somersault
- mass
- Distance/distribution of mass
Three factors that affect the horizontal distance travelled by a shot in flight
- Speed of release: greater speed
- Angle of release: just under 45 degrees
- Height of release: greater the release height
Explain the shape of the flight path of the shot putt
- parabolic flightpath
- weight is the dominant force (mass is high)
- Air resistance will be low
identify vertical forces acting on the gymnast and explain their relationship during the handstand
- weight and reaction
- W=R
- Forces are equal and opposite (net force = 0)
Define angular motion and how it is generated to produce a somersault
- movement of a body about an axis of rotation
- Force applied outside the COM (eccentric force)
Use the angular analogue of newtons first law of motion to explain the concept of conservation of angular momentum
- body will continue to rotate about it’s axis of rotation with constant angular motion
- unless an eccentric force is applied
- Angular momentum= moment of inertia x AV
- once in flight any change to the moment of inertia will cause change in the AV in order to conserve angular momentum
- the performer can change the moment of inertia by manipulating body shape.
Identify two types of spin and the effect of each on a table tennis ball in flight
- Top spin (ball to dip, comes down more quickly)
- Back spin (longer flight path, travel further)
Identify ways that a swimmer can minimise drag
- reduce frontal cross-sectional area
- streamline
- reduce surface affects (smooth surface)
- reduce speed
