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Define an objects instantaneous speed?
the speed at a given instant of time
How to work out average speed?
Average speed= (distance travelled)/(time taken)
When is an object in uniform motion?
and give two quantities which describe this motion.
- When an object is moving at a steady speed in a straight line.
- displacement and velocity.
Define displacement and velocity?
- Displacement: the distance it has travelled in a particular direction.
- Velocity: Its speed in a particular direction
Give the equation used to work out veloctiy?
- (the velocity of an object is the rate of change of its displacement).
state si unit for displacement or distance measured in, time and velocity ?
- Velocity measured in= metres per secound ()
- Displacement or distance measured in= metres(m).
- Time measured in =seconds (s)
What is a vector quantity?
A Vector quantity has both magnitude (size) and direction (e.g: displacement, velocity)
define a scalar quantity?
A scalar quantity has only magnitude. ( e.g: distance, speed)
Describe the 3 motions that are changing on the graph?
- *The straight line sloping up shows that it is going away at a steady speed. ( positive velocity)
- *a horizontal line shows that it is stationary for a while. ( zero velocity)
- *a straight line sloping down shows that it is coming back at a steady speed. (negative velocity)
How would the graph look like if the object is speeding up(acceleration).
What does an object with negative acceleration and positive acceleration suggests?
- negative acceleration: the object is slowing down. Which is sometimes referred to as a deceleration or retardation.
- Positive acceleration: means the object is speeding up.
What does an object with zero acceleration suggests?
the object with zero acceleration either has a uniform velocity(steady speed) or is stationary.
What is the average acceleration of free fall on earth? the average g?
Describe this velocity-time graph?
- *A straight line sloping up indicates steadily increasing speed.(uniform 'positive' acceleration)
- *A horizontal line shows steady speed ('zero acceleration')
- *A straight line sloping down shows steadily decreasing speed. (negative acceleration or deceleration)
What does the gradient of the velocity - time graph shows?
how do you find the acceleration at any instant if the graph is a curve?
find the gradient of the tangent of the curve.
what does a graph with decreasing gradient shows?
- shows decreasing acceleration.
how do you work out the displacement from a velocity-time graph. and why does it work?
The area under the velocity-time graph gives the displacement, because it is the average speed multiplied by the travelling time.