motion

• What is speed defined as?

  The rate of change of distance
• What is the equation to determine the average speed of an object?

  $v =$$\frac{\Delta x}{\Delta t}$
• What is the SI unit for speed?

  ms^-1
• What is instantaneous speed?

  The speed of an object over a very short time interval
• How can instantaneous speed be determined?

  By analyzing the gradient of the tangent of a distance-time graph at a given time
• What is displacement?

  The distance an object has travelled in a given direction
• Why is velocity considered a vector quantity?

  Because it has both magnitude and direction
• What is the formula for velocity?

  $v =$$\frac{\Delta s}{\Delta t}$
• What is acceleration defined as?

  The rate of change of velocity
• What is the formula for acceleration?

  $a =$$\frac{\Delta v}{\Delta t}$
• When is an object considered to be accelerating?

  When its speed is increasing, decreasing, or its direction changes
• What does a flat line represent on a displacement-time graph?

  A stationary object
• What does a line with a constant gradient represent on a displacement-time graph?

  An object with constant velocity
• What does a curved line represent on a displacement-time graph?

  An object that is accelerating or decelerating
• What does the y-coordinate represent on a velocity-time graph?

  The instantaneous velocity of the object at that time
• What does the gradient of the line on a velocity-time graph represent?

  The acceleration of the object

  
• What does a flat line on a velocity-time graph indicate?

  An object travelling with constant velocity
• What does a line with a constant gradient on a velocity-time graph indicate?

  An object that is accelerating at a constant rate

  
• What does a negative gradient on a velocity-time graph represent?

  Negative acceleration
• How can the area under a velocity-time graph be calculated if the graph is linear?

  Mathematically using the area formulas for rectangles and triangles
• What are the four equations of motion for an object travelling with constant acceleration?

  v=u+at, s=ut+½(v-u)t, s=½(v+u)t, v²=u²+2as
• What does the final velocity equation represent?

  The final velocity is equal to the initial velocity plus acceleration multiplied by time
• What does the area under the graph of a velocity-time graph represent?

  The displacement of the object
• What is the significance of the maximum height in vertical motion?

  It is reached when the velocity equals 0
• What is the acceleration due to gravity?

  $g =$$9.81 \text{ ms}^{-2}$
• What is terminal velocity?

  The constant speed an object reaches when the force of gravity is balanced by drag
• How can terminal velocity be determined?

  Using light gates connected to a timer or data logger
• What is the method involving a trapdoor and an electromagnet used for?

  To determine the acceleration of free fall, g
• What happens when the electromagnet is deactivated in the trapdoor method?

  A timer begins, and stops when the trapdoor is hit
• What is the initial velocity of the ball in the trapdoor method?

  0, as the ball is initially at rest
• How can the acceleration of free fall be calculated using the trapdoor method?

  By substituting the known distance fallen and time into the equation $s =$$ut +$$\frac{1}{2} at^2$
• What is projectile motion?

  Motion of an object thrown at an angle to the horizontal
• How are the horizontal and vertical components of projectile motion analyzed?

  Independently, but the time is interchangeable
• What is assumed for all projectile questions at A-level?

  That there is no air resistance
• What are the initial vertical and horizontal velocities for an object projected at an angle?

  Initial vertical velocity is $v \sin \alpha$ and horizontal velocity is $v \cos \alpha$
• What remains constant in the horizontal direction during projectile motion - no forces?

  The horizontal velocity and can be determined with speed/time
• What affects the vertical velocity in projectile motion?

  The acceleration of free fall, g
• How can the time to reach maximum height in vertical motion be determined?

  By calculating when the final velocity equals 0
• What is the significance of resolving resultant velocities in projectile motion?

  To obtain final horizontal and vertical components of motion
• How can the final velocity of a projectile be calculated?

  Using Pythagoras’ theorem from the final horizontal and vertical components