CHS_Physics_Kinematics Graphs Summary

General Principles

We can either describe the graph itself OR the gradient of the graph. For the former, we need to describe (a) If the graph is increasing/decreasing/constant and (b) If the gradient is increasing/decreasing/constant and (c) The direction (positive/negative), if necessary Using the displacement-time graph as an example, we have the following description: The displacement of the object is increasing (because the magnitude is getting larger) at an increasing rate (because the gradient is getting steeper). Hence, our answer is as follows: The displacement of the object is increasing at an increasing rate. For the latter description using the gradient, we need to know: (a) The physical quantity that the gradient represents and (b) Whether the gradient is constant/getting steeper/gentler (c) Whether the gradient is positive or negative Using the displacement-time graph as an example, we have the following description: The velocity (as gradient of displacement-time graph is velocity) is increasing (as the gradient is getting steeper) and positive (as the gradient is positive). Hence, our answer is as follows: The velocity is increasing and positive. (Note the underlined part for both description. Can you see the link between the two?) t / s s / m

Application of General Principles

Displacement-time graph Velocity-time graph Acceleration-time graph Graph Object is at rest The velocity of the object is constant The acceleration of the object is constant Gradient The velocity is zero The acceleration is zero t / s v / m s-1 t / s s / m t / s a / m s-2

Displacement-time graph Velocity-time graph Acceleration-time graph Graph The displacement of the object is increasing at a constant rate The velocity of the object is increasing at a constant rate The acceleration of the object is increasing at a constant rate Gradient The velocity is constant and positive. The acceleration is constant and positive. t / s v / m s-1 t / s s / m t / s a / m s-2

Displacement-time graph Velocity-time graph Acceleration-time graph Graph The displacement of the object is increasing at an increasing rate The velocity of the object is increasing at an increasing rate The acceleration of the object is increasing at an increasing rate Gradient The velocity is increasing and positive. The acceleration is increasing and positive. t / s v / m s-1 t / s s / m t / s a / m s-2

Displacement-time graph Velocity-time graph Acceleration-time graph Graph The displacement of the object is increasing at a decreasing rate The velocity of the object is increasing at a decreasing rate The acceleration of the object is increasing at a decreasing rate Gradient The velocity is decreasing and positive. The acceleration is decreasing and positive. t / s v / m s-1 t / s s / m t / s a / m s-2

Displacement-time graph Velocity-time graph Acceleration-time graph Graph Displacement The displacement of the object is decreasing at a constant rate The velocity o