Science

• What does a journey describe in physics?

  The motion of an object over time
• How can a journey be represented?

  Using a distance-time graph
• What does a distance-time graph show?

  When an object is moving or stationary
• What is plotted on the vertical axis of a distance-time graph?

  Distance travelled
• What is plotted on the horizontal axis of a distance-time graph?

  Time taken
• What does a straight diagonal line on a distance-time graph indicate?

  The object is travelling at constant speed
• What does the gradient of a line on a graph represent?

  The speed of the object
• What is acceleration?

  The rate of change of speed
• How is acceleration shown on a distance-time graph?

  With a curved line that gets steeper
• What does a steeper straight line on a distance-time graph indicate?

  The object is travelling at a faster constant speed
• What does deceleration mean?

  When an object is slowing down
• How is a stationary object represented on a distance-time graph?

  With a flat line
• What does the gradient of a distance-time graph equal?

  The speed of the object
• How do you calculate the gradient of a line?

  Change in y value divided by change in x value
• What are the units for speed if distance is in metres and time is in seconds?

  m/s
• What is the speed calculation if distance is in kilometres and time is in hours?

  km/h
• What is the speed of an object if it travels 8 m in 4 s?

  2 m/s
• What is average speed?

  Total distance divided by total time
• If a journey includes a stop, how is it represented on a distance-time graph?

  As a flat line during the stop
• What is the average speed if you travel 1000 m in 20 minutes?

  50 m/min
• How can you determine when a car is stationary from a distance-time graph?

  By identifying flat sections of the graph
• How can you find the fastest part of a car's journey on a distance-time graph?

  By identifying the steepest section of the graph
• What is the total distance travelled by the car in the example?

  6 metres
• How far did the car travel between 2 seconds and 3 seconds?

  3 metres
• What is the speed of the car between 2 seconds and 3 seconds?

  3 m/s
• What are the key points about distance-time graphs?

  • Represents motion of an object over time
  • Shows when an object is moving or stationary
  • Can calculate speed from the graph
• What are the characteristics of a distance-time graph?

  • Vertical axis: Distance travelled
  • Horizontal axis: Time taken
  • Straight diagonal line: Constant speed
  • Curved line: Acceleration or deceleration
  • Flat line: Stationary object
• How to calculate speed from a distance-time graph?

  1. Identify the gradient of the line
  2. Use the formula: \(gradient = \frac{change~in~y~value}{change~in~x~value}\)
  3. Units depend on distance and time units
• How to calculate average speed?

  1. Total distance travelled
  2. Total time taken
  3. Average speed = Total distance / Total time
• What is the overall force acting on an object called?

  Resultant force
• How do multiple forces affect an object's movement?

  The size and direction determine movement
• What are the steps to draw a free body diagram?

  • Represent the object with a box or dot
  • Draw arrows with a pencil and ruler
  • Draw arrows from the center of the box or dot
  • Label the arrows with force names and sizes
• What does the normal reaction force represent in a free body diagram?

  It acts at right angles to the surface
• What is the resultant force when two forces act in the same direction?

  Add the forces together
• If two forces of 20 N and 10 N act in the same direction, what is the resultant force?

  30 N to the right
• How do you calculate resultant force when forces act in opposite directions?

  Subtract the smaller force from the larger
• What is the resultant force if a ball's weight is 8 N and air resistance is 5 N?

  3 N acting downwards
• What happens if the forces acting on an object are balanced?

  There is no resultant force
• If a car's thrust is 500 N and air resistance is also 500 N, what is the resultant force?


  0 N
• What does it mean if an object is at rest?

  It is not moving