Ch 2 Kinematics Flashcards
Distance
It is the length of the path travelled by the object.
What is displacement?
Displacement is the change in position of an object.
It is also equal to the shortest distance between two points. This distance is written down with a direction making it a vector quantity.
What are the differences between distance and displacement?
Distance: depends on the path, always positive
Displacement: independent of the path taken, can be positive or negative
What is speed?
Speed is rate of change of distance.
It is a scalar quantity so has no mention of direction.
What is velocity?
Velocity is the rate of change of displacement.
It is a vector quantity.
What is acceleration?
Rate of the change in velocity.
It is a vector quantity.
What is Average speed?
Average speed is the total distance travelled over a time interval and is measured in meters per second.
uniform acceleration
Rate of change of velocity is constant.
An object travelling with a uniform acceleration of 5m/s2 experiences an increase in its velocity by 5m/s every 1 sec.
An object travelling with a uniform acceleration of -5m/s2 experiences a decrease in its velocity by 5m/s every 1 sec.
non-uniform acceleration
when the magnitude of acceleration changes over time.
acceleration of free-fall for a body near to the Earth is __________ and is approximately ________ m/ s2
constant , 10
What is the formula for acceleration?
Change in velocity/ Time Taken
a=(v-u)/t
Instantaneous
at a specific point in time.
For a distance-time graph, the _________ never decreases.
distance; it either increases or remains the same
When the object is stationary, the distance-time graph will be ________ line.
Horizontal
The gradient of a distance-time graph is the ________________ of the object.
Instantenous Speed
For straight line with positive gradient, it means that the object is travelling at _________ speed
Uniform
For curves, it means that the object is travelling at ____________ speed
Non-uniform
deceleration is
negative acceleration
the area under a speed-time graph to determine the _______________ for motion with uniform speed or uniform acceleration.
Distance Travelled
In the absence of air resistance, all objects fall with the same acceleration, regardless of their mass.
(True/False)
True
So long as air resistance remains insignificant, the speed of a falling object will increase at a ________ rate, getting larger the longer it falls for.
Steady/uniform/constant
When a parachutist jumps out of an aeroplane, two main forces act:
- Weight (the force of gravity)
- ______________
Air resistance
For a speed time graph:
- If the line is horizontal, the speed is _________ and value of acceleration is ___________.
- If the line slopes upwards then the object is ___________
- If the line goes down then the object is _____________
- constant, zero
- accelerating (speeding up)
- decelerating (slowing down)
When asked to find the distance, start by stating:
distance = area beneath graph
A common mistake is to try and find distance using the distance-speed-time equation. This equation will not work if the _________ is changing.
speed of the object
For a speed-time graph
If the gradient of the line changes then the acceleration of the body must be changing:
A line with constant gradient represents -__________ acceleration (linear motion)
A curved line represents ___________ acceleration – either decreasing (if the gradient gets ________) or increasing (if the gradient gets large)
constant,smaller
Incase of circular motion, The speed remains ____________ but __________ changes at every point.
speed, velocity
The direction of velocity is ___________ to the circular path.
Tangent
