Force Flashcards
What is the relationship between the centre of mass and the application of force ?
A force who’s line of application passes through the centre of mass causes the resulting motion to be linear
A force who’s line of application passes outside its centre of mass causes the resulting motion to be angular. Called an eccentric force = rotation = angular motion
Define a scalar and vector quantity
Scalar - a scalar quantity has only magnitude e.g. speed, mass, distance
Vector - a vector quantity has both magnitude and direction e.g. displacement, velocity, acceleration, momentum, weight
Give the formula for weight
Weight (N) = mass x gravitational force
Weight is a vector quantity
Define both displacement and distance
Distance - Measured in metres. The path a body takes as it moves from the starting to finishing position. Scalar quantity.
Displacement- Measured in metres. Shortest route in a straight line between start and finish position. Vector quantity.
Define speed
Speed - the rate of change of a position. Is a scalar quantity
Given by the formula - distance / time
Define velocity
Velocity - Velocity refers to how fast a body travels in a certain direction. It is the ‘rate of change of displacement. It is a vector quantity.
Velocity = displacement (M) / time (s)
Define acceleration
Acceleration - the rate of change of velocity. When velocity increases, positive acceleration occurs whilst when velocity decreases negative acceleration occurs.
Acceleration - change in velocity / time
Define momentum ?
Is the product of mass and velocity of an object. It is a vector quantity.
Momentum (kg/ms) - mass(kg) x velocity (m/s)
What is the conservation of momentum ?
This occurs when an object or a performer is in flight
When in flight neither mass nor velocity can be altered
What are the 2 type of forces and their definitions ?
Internal forces - generated by the skeletal muscle
External forces - comes from outside the body
Give examples of internal forces
In a layup the forces are generated by the gastrocnemius, quadriceps and gluteals that contract concentrically to plantarflex the ankle & extend the knee and hip in a jump
Give examples of external forces
Air resistance, gravity, weight
How can you categorise external forces ?
Horizontal forces - friction and air resistance
Vertical forces - gravity and weight
What Is a reaction force ?
A force which is generated when 2 objects are in contact with each other
Newtons 3rd law - for every action there is an equal and opposite reaction
What 2 types of friction forces are there ?
Static - force exerted when there is no motion between 2 objects. Force that keeps an object at rest
Sliding - When 2 bodies in contact have the tendency too slip / slide over one another. Friction acts in opposition to motion
