P9- Motion Flashcards
What does the gradient of a line on a distance-time graph represent?
speed
What unit is speed?
metres per second (m/s)
what symbol is speed?
v
What is distance traveled measured in?
metres
What can the d/s*t equation be used to calculate?
the average speed of an object whose speed varies
What should you do in the exam when time is given in minutes or hours in these calculations?
always convert it into seconds
A steeper gradient equals to a?
faster speed
What is velocity?
speed in a given direction
An object that travels at constant velocity travels at what?
a constant speed without changing its direction (straight line)
What is the word used for the distance travelled in a given direction?
displacement
What is the acceleration of an object?
its change of velocity per second
What is the unit of acceleration?
metre per second squared (m/s^2)
Any object with a changing velocity is?
accelerating
How can we work out average acceleration?
change in velocity/ time taken for the change
How to find the change in velocity?
final velocity-initial velocity
The equation of acceleration can be written as?
(final velocity - initial velocity)/ time taken for the change
equation for acceleration as symbols?
a=(v-u)/t
When is the term deceleration or negative acceleration used?
an object slows down
When does a car decelerate?
when the driver brakes
A minus value for acceleration means?
the object is slowing down
How may you want to record how the velocity of an object changes?
-a motion sensor linked to a computer
If you let a trolley accelerate down the runway, what happens?
its velocity increases wih time
If the line is straight in the velocity time graph, what does this mean?
the increase in velocity was the same every second
-the acceleration of the trolley was constant
What happens if you make the runway steeper for the trolley?
the trolely accelerates faster
What would happen to the line on the velocity time graph if acceleration increases?
steeper gradient
What does the gradient of the line on a velocity-time graph represent?
acceleration
What does braking do?
reduces the velocity of a behicle
What happens when a vehicle stops at a set of traffic lights?
the velocity is constant until the driver applies the brakes
If the gradient of the velocity-time graph is zero, what does this mean?
acceleration in this section is zero
When brakes are applied, what happens to the vehicle?
vehicle decelerates and its velocity decreases to zero
What happens to the gradient of the line when brakes are applied?
the gradient of the line is negative
-acceleration is negative
The area under the line on a velocity-time graph represents what?
the distance travelled in a given direction (or displacement)
How can speed and velocity also be described in?
kilometres per hour (km/h)
If speed and velocity are given in km/h, what must be done before plotting them on a graph or using them in?
their values must be converted to metres per second
For an object moving at constant speed, what does the line in a distance-time graph look like?
a straight line sloping upwards
What is the speed of the object is represented by?
the gradient of a line
Why does the gradient represent acceleration?
change of velocity/time taken
To find the distance travelled from the graph…
remember that the area under a line on a velocity-time graph represents the distance travelled
What equation is useful for calculations where the time taken is not given and the acceleration is constant?
v^2 - u^2= 2as
