# I Veocity time graph for a tennis ball during a rally?

1. May 5, 2017

### zoya76

Hi all,
I am trying to draw a velocity time graph for a tennis ball during a rally. I am aware that the horizontal component of the velocity/speed will be constant, assuming negligable air resistance, and that the vertical component of the velocity will be a sawtooth shape. However I am unsure how to put these two components together to get an actual velocity time graph.
Many thanks
ZanyZoya

2. May 5, 2017

### Arman777

The magnitude of the velocity can be written as $v=\sqrt {(v_h)^2+(v_v)^2}$ where;
$(v_h)$:horizontal component of velocity in magnitude and
$(v_v)$:vertical component of velocity in magnitude.

As you said horizontal component will be constant so this is actually one variable function.So using this function and values you can create velocity-time graph

3. May 5, 2017

### nasu

Velocity is a vector so plotting velocity versus time is usually done by plotting the components. You can also plot the magnitude and the angle of the vector versus time.