The function ball_height computes the height of the ball at a given time:

def ball_height(t, v_0=10):
    g = 9.81
    return v_0*t - 0.5*g*t**2

We use this function to plot the height of the ball during the first second of its movement:

%matplotlib inline
%config InlineBackend.figure_format = 'retina'
import matplotlib.pyplot as plt
import numpy as np

t = np.linspace(0,1)

plt.figure(figsize=(4,2))
plt.plot(t, ball_height(t))
plt.xlabel('time (sec)')   
plt.ylabel('height (meters)') 
plt.title('Ball height vs time', fontsize=10)
plt.show()