Displacement time graphs indicate the displacement relative to particular point as a vector. One direction is taken as positive and one direction is taken as negative, so only these this forwards and backwards motion can be displayed. At any time t the displacement can be read off the vertical axis by moving up from a certain time t to meet the graph then along to read off the displacement. For example the displacement at t=7 s below is 20 m.

General Points

  1. The gradient at any point is equal to the rate of change of displacement, or the velocity. In particular a horizontal line has zero velocity or constant displacement.