import matplotlib.pyplot as plt
import numpy
if __name__ == '__main__':
plt.plot([0, 10], [0, 0], marker='o', markersize=8, linewidth=4)
for x in numpy.linspace(3, 5, num=21):
plt.arrow(x, 0, 0, 0.4*(x-3)*(5-x), head_width=0.1, head_length=0.01, length_includes_head=True, color='red')
plt.ylim(-0.5, 0.5)
plt.show()