The velocity-time graph for a uniformly retarded body is a straight line inclined to the time axis with an obtuse angle. How is retardation calculated from the velocity-time graph?

The figure shows the displacement-time graph for four bodies A, B, C, and D. In each case state what information you get about the acceleration (zero, positive or negative).

Draw a velocity-time graph for the free fall of a body under gravity, starting from rest $\left(\mathrm{g}=10 \mathrm{m} {\mathrm{s}}^{-2}\right)$.