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5 Some More Python Essentials
an object’s initial vertical velocity, and then computes height (as it develops with
time), maximum height and flight duration.
The more flexible version of vertical_motion.py then reads,
"""
Module for computing vertical motion
characteristics for a projectile.
"""
def y(v0, t):
"""
Compute vertical position at time t, given the initial vertical
velocity v0. Assume negligible air resistance.
"""
g = 9.81
return v0*t - 0.5*g*t**2
def time_of_flight(v0):
"""
Compute time in the air, given the initial vertical
velocity v0. Assume negligible air resistance.
"""
g = 9.81
return 2*v0/g
def max_height(v0):
"""
Compute maximum height reached, given the initial vertical
velocity v0. Assume negligible air resistance.
"""
g = 9.81
return v0**2/(2*g)
def application():
import numpy as np
import matplotlib.pyplot as plt
import sys
print("""This program computes vertical motion characteristics for a
projectile. Given the intial vertical velocity, it computes height
(as it develops with time), maximum height reached, as well as time
of flight.""")
try:
v_initial = float(input(’Give the initial velocity: ’))
except:
print(’You must give a valid number!’)
sys.exit(1)
H = max_height(v_initial)
T = time_of_flight(v_initial)
print(’Maximum height: {:g} m, \nTime of flight: {:g} s’.format(H, T))
# compute and plot position as function of time
dt = 0.001
# just pick a "small" time step
N = int(T/dt)
# number of time steps
t = np.linspace(0, N*dt, N+1)