Motion Chapter Notes | Physics for GCSE/IGCSE - Year 11 PDF Download

 Page 1


Describing motion
? Speed
? Distance traveled by an object in unit time
? Speed = d/t
? Measures m/s or km/hr or mph(miles per hour)
? Gradient of distance-time graph
? Average speed
? Total distance/ Total time
? S.I = m/s
? Velocity
? Velocity equals to displacement upon time
? V= D/t
? Acceleration
? The rate if change of an object’s velocity
? Acceleration = change in velocity / time taken
? A = v- u/t
? Gradient of speed time graph
? Distance= Speed x time
? Displacement= Object’s overall change in position
? Conversion
? km/hr ? m/s (x 5/18)
? m/s ? km/hr (x 18/5)
? Properties of distance-time graph
? A horizontal line means object is
stationary
? A  straight line means constant speed
? If the gradient increases the object is
speeding up(accelerating)
? If the gradient decreases the object is
slowing down (decelerating)
? If the line is going down, the object is
moving backwards
? The speed of an object is given by the
gradient of the line
? Motion
? Uniform motion
¦ Constant speed/ fixed rate
¦ Object travels equal distance
? Non-uniform motion
¦ Unequal distance
Page 2


Describing motion
? Speed
? Distance traveled by an object in unit time
? Speed = d/t
? Measures m/s or km/hr or mph(miles per hour)
? Gradient of distance-time graph
? Average speed
? Total distance/ Total time
? S.I = m/s
? Velocity
? Velocity equals to displacement upon time
? V= D/t
? Acceleration
? The rate if change of an object’s velocity
? Acceleration = change in velocity / time taken
? A = v- u/t
? Gradient of speed time graph
? Distance= Speed x time
? Displacement= Object’s overall change in position
? Conversion
? km/hr ? m/s (x 5/18)
? m/s ? km/hr (x 18/5)
? Properties of distance-time graph
? A horizontal line means object is
stationary
? A  straight line means constant speed
? If the gradient increases the object is
speeding up(accelerating)
? If the gradient decreases the object is
slowing down (decelerating)
? If the line is going down, the object is
moving backwards
? The speed of an object is given by the
gradient of the line
? Motion
? Uniform motion
¦ Constant speed/ fixed rate
¦ Object travels equal distance
? Non-uniform motion
¦ Unequal distance
¦ Unequal time
? Velocity time graph
? You can find the acceleration
? It shows how the velocity(or speed) of an object
changes overtime
? If the line is horizontal, it is constant (no
acceleration)
? If the line slopes upwards then the object is
accelerating(speeding up)
? If the line goes down then the object is
decelerating(slowing down)
? Deceleration = Negative acceleration
? Calculating distance
? The distance traveled can be found from the area beneath the graph
? If the area beneath the graph forms triangle (the object is accelerating or decelerating) then the
area can be determined by ½ x base x height
? If the area beneath the graph is a rectangle (constant velocity) then the area can be determined
using the formula ? area = l x b
? The acceleration of an object is given by the gradient of the graph ? Gradient = y2-y1/x2-x1
? Lines that slope downwards have negative gradients and so can be said to have negative
acceleration or deceleration
? If the gradient of the line changes then the acceleration of the body must be changing.
? A line with constant gradient represents constant acceleration(linear motion)
? A curved line represents changing accelerating either decreasing(if gradient gets smaller) or
increasing(if gradient gets bigger)
? Free fall
? In the absence of air resistance,all objects will fall with the same acceleration regardless of their
mass
? This acceleration is equal to the gravitational field strength and is approximately 10m/s2 near
the earth’s surface
? So as long as the air resistance remains insignificant, the speed of a falling object will increase
at a steady rate, getting larger the longer it falls for
? Final acceleration = final gradient = rise/run