1. Define an objects instantaneous speed?
    the speed at a given instant of time
  2. How to work out average speed?
    Average speed= (distance travelled)/(time taken)
  3. 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.
  4. Define displacement and velocity?
    • Displacement: the distance it has travelled in a particular direction.
    • Velocity: Its speed in a particular direction
  5. Give the equation used to work out veloctiy?

    • Image Upload 1
    • (the velocity of an object is the rate of change of its displacement).
  6. state si unit for displacement or distance measured in, time and velocity ?
    • Velocity measured in= metres per secound (Image Upload 2)
    • Displacement or distance measured in= metres(m).
    • Time measured in =seconds (s)
  7. What is a vector quantity?
    A Vector quantity has both magnitude (size) and direction (e.g: displacement, velocity)
  8. define a scalar quantity?
    A scalar quantity has only magnitude. ( e.g: distance, speed)
  9. Image Upload 3

    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)
  10. How would the graph look like if the object is speeding up(acceleration).
    Image Upload 4
  11. Describe acceleration and show how to work out acceleration. And give the unit of acceleration.
    • The acceleration of an object is the rate of change of its velocity.
    • Acceleration=Change in velocity/Time taken
    •              Image Upload 5
    • Another way of writing acceleration is
    •  Acceleration= (final velocity- initial velocity)/time
    •                       Image Upload 6
    • acceleration is given in Image Upload 7 (metres per second squared.
    •      where v is the final velocity and u is the initial velocity.

  12. 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.
  13. What does an object with zero acceleration suggests?
    the object with zero acceleration either has a uniform velocity(steady speed) or is stationary.
  14. What is the average acceleration of free fall on earth? the average g?
    9.81Image Upload 8
  15. Describe this velocity-time graph?Image Upload 9
    • *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)
  16. What does the gradient of the velocity - time graph shows?
  17. how do you find the acceleration at any instant if the graph is a curve?
    find the gradient of the tangent of the curve.
  18. what does a graph with decreasing gradient shows?
    • shows decreasing acceleration.
    • Image Upload 10
  19. 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.
Card Set
velocity and displacement