4.3 - Biomechanics
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What are scalar quantities?
Only a magnitude ex. body mass and height, speed
What are vector quantities?
Direction and a magnitude ex. acceleration, velocity, drag, momentum
What does force mean and what’s it’s equation?
The mechanical interaction that goes on between two objects - mass x acceleration
What does speed mean and what’s it’s equation?
The rate at which someone or something is able to move or operate at - distance/time
What does acceleration mean and what’s it’s equation?
The rate of change of velocity - change in velocity/time
What does velocity mean and what’s it’s equation?
The speed of something in a given direction - displacement change/time
What does displacement mean?
The direct distance from a starting point
What does momentum mean and what’s it’s equation?
The quantity of motion of a moving body, measured as a product of its mass and velocity - mass x velocity - mass in motion
What does impulse mean and what’s it’s equation?
Force felt during s collision multiplied by the duration of the collision - force x time - it’s the increase or decrease of an object’s momentum
What is Newton’s first law of motion?
“An object will remain at rest or continue with constant velocity unless acted on by an unbalanced force.”
What is Newton’s second law of motion?
“The acceleration is proportional to, and in the same direction as, the unbalanced force applied to it” - force = mass x acceleration - relates to change in motion
What is Newton’s third law of motion?
When one body/object applies a force to another, the second body/object will apply a force equal in size but opposite in direction to the first body/object. - action = reaction
Explain the conservation of momentum
Conserved = constant During a collision between two people the total momentum of the two people before the collision is equal to the total momentum of the two people after the collision. The momentum lost by person 1 is equal to the momentum gained by person 2.
Define the term centre of mass
The centre of mass is the point in which the mass of the body is evenly distributed
What is a lever?
Rigid structures hinged at one point (fulcrum) to which forces are applied to two other points (effort and load)
Distinguish between first, second, and third class levers
1st class has the fulcrum in the middle 2nd class has the load in the middle 3rd class has the effort or applied force in the middle
What is the equation for angular momentum?
L (angular momentum - something rotating around fixed axis) = I (moment of inertia) x W (angular velocity)
What is torque?
The ability of a force to rotate a body about an axis (T = force x distance)
What does the size of torque rely on?
the size of the force, the direction of the force, how far it is applied from the axis of rotation
What is moment of inertia?
A body’s resistance to a change in its’ state of rotational motion - how difficult it is for a body to rotate about an axis
What does the moment of inertia depend on?
Mass of the object Mass distribution around the axis - more mass further away from the axis gives a greater moment of inertia and it will be more difficult to rotate
What are the three factors that effect the projectile motion of an object?
Angle of release - how high and how far it will reach Height of release - thrown from a height will mean the maximum height and maximum range achieved will be greater Speed of release - how high and how far it will reach
Summarise the Bernoulli principle
The faster a gas or fluid is flowing, the lower it’s air pressure (high speed = low pressure - vise virsa) Lift (magnus effect) acts perpendicular to the direction of motion High pressure beneath the object pushes up to cause lift