Motion

• Speed

  The distance travelled per unit time
• Why is speed a scalar quantity?

  It only contains magnitude
• Average speed

  The total distance travelled divided by the total time taken
• What does velocity describe that speed does not?

  Magnitude and direction of motion
• Velocity

  The rate of change of displacement with respect to time
• Acceleration

  The rate of change of velocity
• What does a positive acceleration indicate?

  The object is speeding up
• What does negative acceleration indicate?

  The object is slowing down
• What is the acceleration of an object with constant velocity?

  0
• How do calculate acceleration from a velocity-time graph?

  Acceleration is calculated as the gradient of a velocity-time graph
• What does a straight line on a distance-time graph represent?

  Constant speed
• What does the slope of a distance-time graph represent?

  The object's speed
• What does a steep slope on a distance-time graph represent?

  A high speed
• What does a flat, horizontal line represent on a distance-time graph?

  The object is stationary
• What does a curve on a distance-time graph indicate?

  Changing speed
• State how changing speed is represented on a distance-time graph

  By a curve
• What is the equation for calculation speed from a distance-time graph?

  Gradient=Δy/Δx
• How can you determine the duration of a certain activity from a distance-time graph?

  From the length of a flat section a distance-time graph
• How do you calculate the total distance from a distance-time graph?

  By identifying the value of the final point on the line representing distance
• How can interpret a flat, horizontal line on a speed-time graph?

  Acceleration is zero
• What represents constant speed on a speed-time graph?

  A flat line
• What does the area under a speed-time graph represent?

  Distance travelled by the object
• What does a steep slope on a speed-time graph indicate?

  Large acceleration or deceleration
• When do all objects fall with the same acceleration?

  In the absence of air resistance
• When does acceleration of free fall remain constant?

  Regardless of an object's mass. But only when air resistance is negligible
• Terminal velocity

  Constant speed reached by a falling object when the upward force of drag equals the downward force of gravity, resulting in zero acceleration.
• Equation for weight

  W=mg

  W- weight newtons (N)

  m- mass kilograms (kg)

  g- acceleration of freefall (m/s^2)
• Air resistance

  The frictional force exerted by air particles on objects moving through air, which opposes the direction of motion
• How does air resistance affect the motion of falling objects?

  It opposes the motion of objects falling through air, exerting an upward force that increases with the object's speed
• What is the relationship between the forces of weight and air resistance during free fall?

  During free fall, weight acts downwards while air resistance acts upwards. As the speed of the object increases, air resistance increases until it equals the weight and terminal velocity is reached.
• How does terminal velocity affect the acceleration of a falling object?

  Terminal velocity occurs when the acceleration of a falling object becomes zero because the upward drag force equals the downward force of weight, resulting in a constant speed.
• Describe air resistance during the fall of a skydiver

  Constant
• Weight

  Weight is the gravitational force exerted on an object with mass