# Motion

• Motion: Refers to any change in position of an object with respect to its surroundings in a given period of time. The motion is observed by attaching a frame of reference to an observer and measuring the change in position of the object in relation to that frame.

• Distance: This is the measure of “how much ground” an object has covered during its motion, regardless of its starting or ending point. Distance is a scalar quantity that only has magnitude and is usually measured in metres (m).

• Displacement: While distance covers the ground an object has travelled, displacement refers to how far the object is from its starting point. It is a vector quantity, which includes both the magnitude (length) and direction. For example, ‘15 metres north’ is a displacement.

• Speed: This is essentially how fast an object is moving. It can be calculated by dividing the distance an object has travelled by the time it took. Speed is also a scalar quantity, often measured in metres per second (m/s).

• Velocity: Similar to speed, but velocity also includes information about the direction of the motion. It’s a vector quantity expressed as the rate of change of displacement. It’s determined by dividing the displacement by time.

• Acceleration: This is the rate at which an object changes its velocity. Acceleration occurs when an object changes its speed, direction, or both. It is a vector quantity typically measured in metres per second squared (m/s^2). The formula for acceleration is ‘change in velocity / time taken’.

• Deceleration or Negative Acceleration: This happens when an object slows down. It’s the rate at which an object decreases its velocity. It’s also a vector quantity.

• Time: Time is used to quantify the duration of motion. It is a scalar quantity and is usually measured in seconds (s).

• Graphical Representation: Motion can be represented graphically with distance-time graphs and velocity-time graphs. The gradient of a distance-time graph represents speed, while the gradient of a velocity-time graph represents acceleration.

• Straight Line Motion: This is motion along a straight line. One dimensional motion can be forward or backward.

• Equations of motion: They are mathematical equations that describe the motion of an object under the condition of constant acceleration. The three key equations you need to know are: v = u + at, s = ut + 0.5at^2, and v^2 = u^2 + 2as, where v is final velocity, u is initial velocity, a is acceleration, s is displacement, and t is time.

Remember to practise calculations using these equations and interpreting motion graphs, as they are commonly tested in exams. Mastering these parameters and concepts is essential to understanding and describing motion in physics.