1.2 - Kinematics Flashcards
What is dispalcement?
the distance of that body from a fixed starting point (in a straight line)
What is speed?
The distance travelled per unit time
What is velocity?
the rate of change of displacement
What is acceleration?
Rate of change of velocity
The __________ of velocity is the speed of the body. However, the velocity is a _____, meaning that there could be a change in ______.
Magnitude
Vector
Direction
The mean speed/ velocity is the average measured over a significant amount of time. Give the equations for mean speed and velocity.
mean speed = distance travelled/ change in time
mean velocity = change in displacement / change in time
Instantaneous is the speed or velocity at any one instant. Give the equations for instantaneous speed and velocity.
Instantaneous speed = speed of a body at a time (rate of change of distance)
Instantaneous velocity = rate of change of displacement at a time
Acceleration of a body is a vector quantity. Give the equation for mean acceleration and instantaneous acceleration?
Mean accel = change in velocity / change in time
How to you calculate the ___ from a displacement - time graph.
Average velocity between 2 points
Instantaneous velocity
Average V = divide the change in displacement between those two points by the time between them. A-B / T (gradient)
Instantaneous V= gradient of tangent to the curve at that point
Note: if the graph has non-straight lines, the gradient is changing so the velocity is changing and therefore the body is accelerating
Refer to NC 1
How do you calculate_______ from a velocity - time graph
mean acceleration
instantaneous acceleration
change in displacement
Mean accel = gradient
Instantaneous accel = gradient of tangent to that point
Change in displacement = total area under the graph ( treating areas formed by positive velocity as positive and areas formed by negative velocity as negative)
The difference between speed-time and velocity-time graphs is visible when the _____ becomes _____ and dips below the axis. On a ______ time graph the line will pass below the time axis but on _____-time graph it will never do so
velocity
negative
velocity
speed
What are the 4 SUVAT equations?
V = u + at
V2 = u2 + 2ax
X = (v + u / 2)t
X = ut + 1/2at2
You assume in SUVAT equations the acceleration is constant (e.g. air resistance is negligible)
Refer to NC 2 and NC 3
In a gravitational field, if a body is moving freely, there is no _______ forces, the only force acting is the _____. _____ acts vertically. If an object has both vertical and horizontal components the horizontal component has no ________ but the vertical does so we can apply v = x / t
resistive
weight
weight
acceleration
With air resistance, falling objects can reach their terminal velocity. This means you cannot use the kinematic equations as the acceleration is not constant. What is terminal velocity?
When an object is falling and the forces of air resistance and weight are equal to one another so the object has no acceleration and falls at a constant velocity.