Biomechanics Flashcards
What is the definition of Mass?
Mass is the quality of matter the body possesses
Acceleration is…
the rate of change of velocity
How would you calculate acceleration?
Change in velocity (ms-1)
———————————– = Acceleration (m/s2)
Time (seconds)
Displacement (m)
———————— =
Time Taken (s)
Velocity (metres/second)
This is the gravitational force exerted on an object and the unit is Newtons (N)
Weight
EQUATION: How is speed measured?
Distance covered (m) ------------------------------ = Speed (m/s) Time taken (s)
The path a body takes as it moves from the starting to the finishing point
Distance
The product of the mass and velocity of an object. Measured in kgm/s
Momentum
What is displacement?
The shortest route in a straight line between starting and finishing point (A to B quickest)
EQUATION: Weight (kg) =
Mass (kg) x gravitational field strength (N/kg)
What is Linear motion?
Motion in a straight or curved line, with all body parts moving the SAME distance at the SAME speed in the SAME direction
What is Newton’s First Law of Motion also known as?
The law of inertia
What does Newtons First Law of Motion state?
A force is required to change the state of a motion
The law of acceleration is also called…
Newtons Second Law of Motion
What is Newtons Second Law of Motion?
The magnitude (size) and direction of the force determines the magnitude and direction of the acceleration.
AKA. Force = mass x acceleration (F=ma)
This law describes what happens when two bodies (or objects) exert forces on one another - equal and opposite reaction (e.g. a goalkeeper)
Newtons Third Law of Motion - the law of action/reaction
The point of balance of a body…
the centre of mass
Why does the centre of mass always change?
As the body is constantly movinh
Who’s centre of mass is slightly higher in the body? Males or females?
Males as more weight is concentrated in their shoulders and upper body whereas females have more body weight at their hips
Give FOUR factors affecting stability?
- The HEIGHT of the centre of mass - lower increases stability
- Position of the line of gravity should be central over the base support to increase stability
- Area of the support base - more contact points increases stability
- MASS of performer - greater mass increases stability due to increased inertia
What are the two measurements used in linear motion?
- Scalar quantity
2. Vector quantity
Scalar quantity is…
Only described in terms of size or magnitude
E.g. mass, distance and speed
Vector quantity is…
Described in terms of magnitude (size) and direction
E.g. weight, acceleration, displacement, velocity and momentum
What does a force do?
Change a body’s state of motion
Give an example of two types of forces
Internal force - skeletal muscles contract
External force - outside the body
Give an example of a specific External force
Air resistance, friction, weight and gravity
Using a high jumper, explain why a large internal force from the leg muscles is needed?
To create a big action force in order to achieve as much vertical displacement (height) as possible
When drawing forces using vectors, how is the magnitude/size of the force reflected?
Through the length of the arrow drawn
EQUATION: Impulse =
force x time
What will an increase impulse result in?
An increase in the rate of change of momentum which causes a large change in velocity
How can using impulse to increase momentum be achieved?
Through increasing the amount of muscular force that is applied and through increasing the amount of time in which a force is applied
Impulse = force x time
Give an example of how a gymnast can use impulse to decrease momentum
When landing the gymnast flexes her hip, knee and ankle which extends the time of force on the ground (how long the feet are in contact with the mat) and this allows the gymnast to control the landing
Using a 100m sprinter in a race, how does impulse effect the race?
- START OF THE RACE = the net impulse is positive which shows the sprinter is accelerating.
- MIDDLE OF THE RACE = both positive and negative impulses are equal (net impulse is zero) which means the sprinter is running at a constant velocity
- END OF THE RACE = the net impulse is negative which shows the sprinter decelerating
Static and Sliding are two types of what?
Friction
When does Static friction occur?
Before an object starts to slide