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Module 3 - Chapter 3 - Motion - Coggle Diagram
Module 3 - Chapter 3 - Motion
Average speed
Total distance travelled/ total time taken
Distance time graphs
Distance on y axis
Time on x axis
Stationary objects are shown by a straight horizontal line
An object at constant speed is shown by a straight line
Gradient of the line = speed of the object
Instantaneous speed
Speed of the car over a very short interval of time
Found by drawing a tangent to the distance - time graph at the time and then determining the gradient
Greater gradient = greater instantaneous speed
Rate of change of distance
Average velocity
Average velocity = Change in displacement/ time taken
Displacement time graphs
Displacement is on the y axis
Time is on the x axis
Straight line with positive gradient in the positive suggests the object is moving away from the start point
Straight horizontal line means the object is stationary
Straight line with a negative gradient in the positive suggests the velcotiy is negative and the object is moving towards the start point
Staight line wtih negative gradient in the negative suggests the velocity is negative and objects is moving away from start point
Straight line with positive gradient in negative suggests the velocity is positive and the object is moving towards the start
Acceleration
The rate of change of veloctiy
Velocity time graphs
Acceleration can be determined by the gradient
Straight line with a constant, positive gradient = constant acceleration
Straight line of 0 gradient = constant velocity (0 acceleration)
Straight line with cosntant negative gradient = constant deacceleration
Curve with changing gradient = acceleration is changing
Calculating displacement
Area under the graph
For instantaneous velocity, if the change in time is very small, the displacement will be the velocity at that time
Displacement = area under the graph
If you add more instantaneous velocities over a longer period of time, the area under the curve is thetotal displacement of the object
Constant accelerations
Break the areas into rectangle and rightangled triangles
Changing accelerations
Counting squares
Equations of motion
Stopping distance
Components
Stopping distance - Total distance travelled from when driver first sees reason to stop, to when vehicle stops
Thinking distance - distance travelled between the driver first seeing reason to stop to moment break is applied
Braking distance - distance travelled from moment break is applied until vehicle stops
Factors affecting distances
Speed of vehicle
condition of breaks
condition of the road
weather conditions
Thinking distance = speed x reaction time
Stopping distance = thinking distance + braking distance
Free fall and g
Acceleration due to gravity
Object released on earth will accelerate vertically downwards towards the centre of the earth
An object accelerating under gravity is said to be in freefall
Determining g
Electromagnet holds small steel ball above trapdoor
When current switches off, timer is triggered, EM demagnetises and ball falls
When ball hits trapdoor, electrical contact is broken and time stops
Projectile motion
Vertical veloctiy changd due to acceleration of free fall
Horizontal velocity remains constant
Vertical and horizontal motions are independent
