Biomechanic principles (i.e newton's laws) Flashcards
(16 cards)
Newton’s first law of inertia
-Newton’s first law of inertia states that an object will remain at rest or at a constant velocity unless acted upon by an external force
-For example a golf ball on a tee is at rest, and will not move unless shit by a golf club (acted upon by an external force)
-The higher the mass of the object the higher the inertia of the object
Newton’s second law of acceleration
-Newton’s second law of acceleration states that the acceleration of an object is proportional to the force applied, and occurs in the direction of the force
-This is also dependent of the mass of the object as Force=massx acceleration
-For example if roger Federer hits the ball with more force during a serve it will accelerate faster
Newton’s third law
-Newton’s third law states that for every action there is an equal and opposite reaction (e.g a 100m sprinter applies a large force to the ground with his foot and the ground applies and equal and opposite reaction back to the foot of the sprinter)
If weight= reaction force
-There will be no change in vertical acceleration, or the object will remain at constant velocity
If weight> reaction force
-If weight is greater than reaction force then there will be vertical deceleration
If weight< reaction force
-If reaction force is greater than weight then there will be vertical acceleration
Horizontal forces
-Air resistance opposes the direction of the force
-Friction opposes the sliding motion of an object that is making contact with the ground
If air resistance =friction
-if air resistance= friction then there will be no change in motion or the object will remain at constant velocity
if air resistance> firction
-If air resistance is greater than friction then there will be horizontal acceleration
If friction> air resistance
If friction is greater than air resistance then horizontal deceleration will occur
Factors affecting friction
Characteristics of ground surface: Rougher ground surface=more friction and smoother ground surface means less friction
Characteristics of contact surface: Rougher contact surface= more friction and smoother contact surface means less friction
-Temperature: higher temperature means more friction
-Mass- Higher mass = higher friction with the ground
Maximising friction
-Increase roughness of contact surface e.g wearing studded football boots when playing on a muddy pitch
-Increase temperature e.g tire heaters in the F1 allow the tires to have greater friction with the track
-Increase mass e.g give the call to a prop to take into contact in a rugby game on a muddy pitch as they would have the most friction
Minimising friction
-Increase smoothness of contact surface e.g ski wax on skis to reduce the contact friction with the snow
Factors affecting air resistance
-Velocity= the higher velocity someone is travelling at, the more air resistance they will experience
-Frontal cross-sectional area= objects with a larger frontal cross-sectional area will experience more air resistance
-Mass= the greater the mass of an object the more air resistance they will experience
Minimising air resistance
-Reduce frontal cross-sectional area e.g a skier uses a downhill crouched position which minimises air resistance to the body
-Cyclists have adopted an aerofoil shape helmet, which is streamlined to minimise air resistance
Calculations and descriptions of force
Force- a push or pull that alters a state of motion (newtons)
Weight- a vertical force that acts downwards from the centre of mass of an object, this is also the force that the earth exerts on the mass of a body (N)
Acceleration- the rate of change of velocity (m/s)
Momentum- the quantity of motion that an object possesses (Kgm/s)
