Linear motion Flashcards
Define scalar quantity
When measurements only determined in terms of magnitude
Define vector quantity
When measurements described in magnitude and direction
What are the scalar measuremnts?
Mass, distance, speed
What are the vector measurements?
Weight, acceleration, displacement, velocity, momentum
Define mass
The quantity of matter the body possesses
Define weight
The force on a given mass due to gravity
Define distance
The path a body takes as it moves from start to finish position
Define displacement
Shortest route in a straight line between start and finish position
Define speed
The rate of change of distance
Define velocity
The rate of change of displacement
Equation for speed
Speed (M/S) = Distance (M) / Time taken(s)
Equation for velocity
Velocity (M/S) = Displacement (M) / Time taken (S)
Define acceleration
The rate of change of velocity
Equation for acceleration
Acceleration (m/s^2) = (Final velocity-initial velocity)/ Time (s)
Define momentum
The product of mass and velocity of an object in kgm/s
What are the 2 types of force
Internal
External
Define external force
Comes from outside the body
Define internal force
Generated by skeletal muscles
What are the vertical forces?
Weight
Reaction force
What are Newtons 3 laws of motion
1)Law of inertia
2)Law of acceleration
3)Law of Reaction
What is the law of inertia?
An object will remain stationary or in constant motion in a straight line unless another force is exerted on it
What is the law of acceleration?
Acceleration of an object is directly proportional to the force exerted on it and inversely proportional to its mass
What is the law of reaction?
When 2 objects interact, they exert equal and opposite forces on each other
Define reaction force
Occurs when 2 bodies are in contact with each other
What are the horizontal forces?
Friction
Air resistance
Define friction
Force that occurs when 2 or more bodies are in contact with one another
What are the 2 types of friction force?
Static
Sliding
What is static friction?
Force exerted on one surface by another when there is no motion between the surfaces
What is sliding friction
Where 2 bodies in contact have a tendancy to slide over one another
When drawing arrows on a diagram, which was does the friction arrow go when static friction occurs?
In the direction of motion
When drawing arrows on a diagram, which was does the friction arrow go when sliding friction occurs?
Against the direction of motion
What factors affect friction?
Surface characteristics
temp of surface - More temp means less friction
Mass of object - more mass means more friction
Define air resistance
Force that opposes the motion of body travelling through air
What factors affect air resistance
Velocity - greater velocity greater resistance
Cross sectional area - larger area means large resistance
Shape and surface characteristics - smoother and more streamlined reduces resistance
Define impulse
Time taken to apply force to an object
Impulse equation
Impulse (N s)= Force (N) X Time(s)
N s = newton seconds
NOT PER SECOND
How can impulse be used to decrease the momentum of an athlete when running?
Increase the contact time between the foot and ground to increase time force is exerted to slow the performer
How can impulse be used to increase momentum of an athlete during a hammer throw?
Performer may add 2 or 3 extra swings to prolong the time the athlete is adding force to his swing
