Mod 1 Kinematics
,Kinematic Notes
Quantities and Units
The difference between mass and weight
Mass - amount of matter (kg)
Weight - Force due to gravity (N)
The difference between speed and velocity
Speed - how far we travel in a certain amount of time
Velocity - is speed combined with direction
What is kinematics
Kinematic is the description and analysis of the motion of an object without studying the cause
of the motion.
Quantity SI Units
Speed M/s
Acceleration m/ss
Force N
Energy J
Momentum Kg / ms
Graphs
Plot the independent variable on the x axis and the dependent variable on the y axis
y = mx+b
Quantitative analysis area under graph
S = vt
Vectors quantities vs vector quantities
A scaler is any quantity that has a magnitude but does not have a direction.
,A vector is any quantity that has magnitude and a direction associated with it.
Vectors are normally represented as arrows, the length of the line represents the magnitude of
the vector in some units.
Dealing with 1 dimension we can only have two opposite directions (left/right, up/down) which
we can indicate direction using positive and negative numbers.
The negative sign reverses the direction. Since we defined motion to the right as positive,
negative values are in the opposite direction i.e. to the left.
Vector addition and subtraction
When adding two vectors such as two displacement vectors s1 + s2 the vectors are joined head
to tail
The resultant vector or final vector spans from the tail of the first vector to the head of the
second vector.
The vector subtraction s1 - s2 is equivalent to the vector addition s1 + (-s2)
Distance and displacement
Distance is a scalar quantity. It refers to the length of the entire path travelled by an object
Displacement is a vector quantity. It refers to the change in position of an object or the
difference between where it began and where it ended.
Displacement can be zero even if the distance travelled is very large.
Speed
Speed is a scalar quantity which measures how fast or slow an object is moving. It measures
distance travelled per unit time.
Instantaneous speed vs Average speed
Instantaneous speed describes the speed of an object at a specific instant in time during its
journey.
- Since a car ride involves many changes in speed the instantaneous speed of the vehicle
during the car ride also varies from zero to quite high speeds.
Average speed is defined as the total distance travelled over a period of time.
, For example a 100 metre sprinter who travels a distance of 100m in 11 seconds has an aver
speed of 100/11 = 0.91 metres per second
Average speed = distance travelled / time taken
V = s/t
The average speed depends on the total distance travelled during a time interval whereas the
instantaneous speed measures the speed of an object at a specific instant in time during its
journey.
Velocity
Velocity measures how quickly or slowly an object's displacement or position is changing.
Velocity is a vector quantity and therefore students must provide both magnitude and direction
when describing it.
Instantaneous velocity
Instantaneous velocity describes the velocity of an object at a specific instant in time during its
journey.
Average velocity is defined as the rate of change of displacement over an interval of time
Average velocity describes how displacement has changed during a time interval and does not
describe how the velocity varies at any instant along the journey.
Average velocity = change in displacement / time taken
V-> = s->/t
Average speed vs average velocity
Velocity conveys information about the direction of movement whilst speed does not. We must
be very careful not to confuse speed with velocity
Average speed: The distanced travelled over a period of time
Acceleration
Acceleration is defined as the rate of change of an object's velocity with respect to time. It
measures of how quickly or how slowly the velocity is changing.
,Kinematic Notes
Quantities and Units
The difference between mass and weight
Mass - amount of matter (kg)
Weight - Force due to gravity (N)
The difference between speed and velocity
Speed - how far we travel in a certain amount of time
Velocity - is speed combined with direction
What is kinematics
Kinematic is the description and analysis of the motion of an object without studying the cause
of the motion.
Quantity SI Units
Speed M/s
Acceleration m/ss
Force N
Energy J
Momentum Kg / ms
Graphs
Plot the independent variable on the x axis and the dependent variable on the y axis
y = mx+b
Quantitative analysis area under graph
S = vt
Vectors quantities vs vector quantities
A scaler is any quantity that has a magnitude but does not have a direction.
,A vector is any quantity that has magnitude and a direction associated with it.
Vectors are normally represented as arrows, the length of the line represents the magnitude of
the vector in some units.
Dealing with 1 dimension we can only have two opposite directions (left/right, up/down) which
we can indicate direction using positive and negative numbers.
The negative sign reverses the direction. Since we defined motion to the right as positive,
negative values are in the opposite direction i.e. to the left.
Vector addition and subtraction
When adding two vectors such as two displacement vectors s1 + s2 the vectors are joined head
to tail
The resultant vector or final vector spans from the tail of the first vector to the head of the
second vector.
The vector subtraction s1 - s2 is equivalent to the vector addition s1 + (-s2)
Distance and displacement
Distance is a scalar quantity. It refers to the length of the entire path travelled by an object
Displacement is a vector quantity. It refers to the change in position of an object or the
difference between where it began and where it ended.
Displacement can be zero even if the distance travelled is very large.
Speed
Speed is a scalar quantity which measures how fast or slow an object is moving. It measures
distance travelled per unit time.
Instantaneous speed vs Average speed
Instantaneous speed describes the speed of an object at a specific instant in time during its
journey.
- Since a car ride involves many changes in speed the instantaneous speed of the vehicle
during the car ride also varies from zero to quite high speeds.
Average speed is defined as the total distance travelled over a period of time.
, For example a 100 metre sprinter who travels a distance of 100m in 11 seconds has an aver
speed of 100/11 = 0.91 metres per second
Average speed = distance travelled / time taken
V = s/t
The average speed depends on the total distance travelled during a time interval whereas the
instantaneous speed measures the speed of an object at a specific instant in time during its
journey.
Velocity
Velocity measures how quickly or slowly an object's displacement or position is changing.
Velocity is a vector quantity and therefore students must provide both magnitude and direction
when describing it.
Instantaneous velocity
Instantaneous velocity describes the velocity of an object at a specific instant in time during its
journey.
Average velocity is defined as the rate of change of displacement over an interval of time
Average velocity describes how displacement has changed during a time interval and does not
describe how the velocity varies at any instant along the journey.
Average velocity = change in displacement / time taken
V-> = s->/t
Average speed vs average velocity
Velocity conveys information about the direction of movement whilst speed does not. We must
be very careful not to confuse speed with velocity
Average speed: The distanced travelled over a period of time
Acceleration
Acceleration is defined as the rate of change of an object's velocity with respect to time. It
measures of how quickly or how slowly the velocity is changing.
