While the terms Position, Distance, and displacement are often used interchangeably, in the context of Physics they mean very specific things. The term 'Position' refers to the absolute distance of an abject to an initial position. 'Distance' refers to the total amount that an object travels, including if it backtracks on itself. 'Displacement', or change in position, refers to the distance between an object's starting point and its ending point, even if it backtracks.
Position-time graphs give us information about the initial position, speed, direction, velocity and acceleration of an object. The Y-intercept represents the initial position at the object, or the position at time = 0. The slope of the graph represents the velocity of the object, in units of distance/time. If the graph has a positive slope, the velocity is positive and a negative slope represents a negative velocity. The steepness of the slope represents the object's speed. An upward curve on a position-time graph represents positive acceleration while a downward curve represents negative acceleration.
Velocity-time graphs give us information about the speed, direction, velocity and acceleration of an object. The Y- intercept on a velocity time graph represents the initial velocity of an object. The slope of the graph represents the acceleration of the object, as the Y value represents its velocity at a given time. Therefore, the acceleration is given in Distance/Time/Time, or Distance/Time squared. If The graph is a flat line, The object is moving at a constant velocity or is at rest.
A velocity-time graph can also tell us the distance and displacement of an object. The area beneath the line of the graph when velocity is positive tells us the positive distance the object travels. When the velocity is negative, the area between the line of the graph and the time axis represents the negative distance an object travels. An object with positive then negative (or vice versa) velocities would backtrack on itself and have a displacement which is different than its total distance.
PhysicsEH
Objects with a constant acceleration can be represented by graphs, motion maps, or written descriptions. A motion map consists of snapshots of an object's position at equal time intervals.
There are also equations that help to solve constant acceleration problems. They are:
If all but one of the variables are known, we can solve for the unknown algebraically. For example:
Initial Velocity: 0m/s
Final Velocity: 10m/s
Time: 40 seconds
Acceleration: Unknown
10m/s = 0m/s + a*40 seconds
10m/s = a*40 seconds
0.25m/s/s = a
Final Velocity: 10m/s
Time: 40 seconds
Acceleration: Unknown
10m/s = 0m/s + a*40 seconds
10m/s = a*40 seconds
0.25m/s/s = a