position-time graphs

On a position-time graph, how do you find:

a. Position?
b. Displacement?
c. Distance?
d. Velocity (if constant)
e. Average Velocity
f. Velocity (if not constant)


[ btw.. this is grade 11 physics ] =)

a. Position
Take the position coordinate. If you are plotting position on y axis and time on x axis, then y coordinate of any point gives the position at that point.

b. Displacement
Read initial and final positions from the graph as explained in (a). Take the difference between them (final position - initial position). This gives the displacement

c. Distance
Mark the start and end points in the graph. Start and end points mean the points between which you have to find distance. In between those two mark the points at which the graph is going from up to down or from down to up. So now you have several points. These points divide the graph into different parts between the start and the end points. For each part, calculate the displacement as explained in (b). Take its absolute value, which means, if it is negative, then make it positive. That gives the distance for that part. Likewise find distances for all the parts and add them.

d. Velocity (if constant)
If velocity is constant, then the graph is a straight line. The gradient of the line gives the velocity.

e. Average Velocity
Find displacement between initial and final positions as explained in (b). Read time coordinates of those points. Final time coordinate - initial time coordinate = time taken.
Average velocity = displacement/time taken

f. Velocity (if not constant)
Draw a tangent to the curve at the point at which you want to find the velocity. Find the graident of this tangent.

If you have some graphs for which you want to ask these questions, then attach the graphs here.