CH 2: Kinematics

• Kinematics is the study of motion which includes distance versus displacement, speed versus velocity, and acceleration.
• Distance is the total length covered between two points and is a scalar quantity.
• Displacement is the straight line distance in a specific direction between an object and a specific point and is a vector quantity.
• Speed is the rate of change of distance which means distance changes over a period of time and is a scalar quantity.
• Velocity is the rate of change of displacement which means displacement changes over a period of time and is a vector quantity.
• Acceleration is the rate of change of velocity and is a vector quantity.
• The SI unit for distance and displacement is meters symbolized as 'm'.
• The distance between two points can be calculated by subtracting the starting point from the ending point.
• The speed of an object is determined by dividing the total distance traveled by the total time taken.
• The average speed of an object is calculated by dividing the total distance traveled by the total time taken when the speed of the object is zero.
• Uniform speed or constant speed is when the speed of an object does not change throughout the whole journey.
• The formula for speed is distance over time.
• For non-uniform or non-constant speed, the average speed is calculated by dividing the total distance traveled by the total time taken.
• The SI unit for acceleration is meters per second squared symbolized as 'm/s^2'.
• When the gradient curves down or is a set phase, the gradient decreases, meaning acceleration decreases.
• The negative gradient curves up on the speed time graph, indicating decreasing deceleration.
• The positive gradient curves up on the speed time graph, indicating increasing acceleration.
• A particle is moving forward at a speed of 6 meters per second and takes 5 seconds to stop and reverse, resulting in a final speed of 4 meters per second.
• The change in velocity is calculated as the final velocity minus the initial velocity, resulting in a negative 10 meters per second.
• The acceleration is calculated using the formula 'a' equals 'b' minus 'u' over 'delta t', where 'b' is the final velocity, 'u' is the initial velocity, and 'delta t' is the time.
• When the gradient is zero or is horizontal line, the speed is zero, indicating the object is at rest or stationary.
• Deceleration is used to describe an object moving at decreasing velocity, which can be interpreted as a negative acceleration.
• When the gradient is constant or a straight line, the object moves at constant speed.
• When the gradient curves up or is a smiley face, the gradient increases, meaning acceleration increases.
• The minimum point of the curve on the speed time graph is where the gradient is zero, indicating zero acceleration.
• A straight line on the speed time graph indicates constant acceleration.
• The change in speed is calculated as the difference between the final speed and the initial speed, resulting in a negative 2 meters per second.
• The gradient of the distance time graph is equivalent to the rate of change of distance, which is speed.
• The area under the graph of a speed time graph gives the total distance traveled within the period of time bounded under the graph.
• The general formula for acceleration is change in velocity over time taken, represented as 'a' is 'delta v' over 'delta t'.
• A steeper line on the speed time graph indicates a higher constant acceleration.
• The formula x equals to half (u + v) times t can be used when the question does not provide the final speed.
• The formula x = half (u + v) times t can be rewritten as s equals to u t plus half a t squared, where s is the total distance traveled.
• The trapezium formula is used to calculate the area under the graph.
• The three important formulas from the linear speed time graph are: u + a t squared equals to u squared + 2x, v equals to u plus a t, and x equals to half (u + v) times t.
• The total distance traveled between points P1 and T2 can be calculated using the formula v = u + at, where v is the final speed, u is the initial speed, and a is the acceleration.
• The total distance traveled can also be calculated using the formula x = half (u + v) times t, where x is the total distance traveled, u is the initial speed, v is the final speed, and t is the time taken.
• When the object reaches its terminal velocity at t e, the air resistance equals to the weight of the falling object, net force is zero, and the object stops accelerating.
• When air resistance equals to the weight of the falling object, net force is zero and the object reaches terminal velocity.
• The maximum point of the curve is when the gradient is zero, indicating that acceleration is zero.