Question

使用公式KE=1/2*m*(v**2)，如何在给出KE时找到速度。

例如，质量为10，KE为50000.0。我试过这种方式：

import math

print("Determining the speed to match the Kinetic Energy of the bowling ball dropped in the desert:")
mass = eval(input("Enter the mass of the bowling ball:"))
KE = eval(input("The Kinetic Energy of the ball with a mass of 10 at 100 MPH is:"))
v=0
print("Mass", " ", "Velocity to reach",KE )
for y in range(140, 321, 15):
    v = math.sqrt(2*KE*(1//mass))
    mass+=15
    print (y," ", v)

但继续得到结果：

Mass   Velocity to reach 50000.0
140   0.0
155   0.0

我应该在哪里修复以获得结果：

Mass     Velocity to reach 50000.0
140      26.72612419124244
155      25.4000254000381

Answer 1

以下是您应该做的事情：

mass = float(input("Enter the mass of the bowling ball:"))
KE = float(input("The Kinetic Energy of the ball with a mass of 10 at 100 MPH is:"))
v=0
print("Mass", " ", "Velocity to reach",KE )
for y in range(140, 321, 15):
    v = math.sqrt((2*KE)/mass)) # no need for * (1/mass), just divide
    mass+=15
    print (y," ", v)

值得注意的是，您正在+=上调用增量运算符mass。因此，一旦您进行了迭代，mass将不再是10。因此，再次运行循环会产生不同的结果。

修改

从评论中，您似乎希望mass从140开始。如果是，则没有理由要求用户mass为input()。只需执行以下操作：

KE = float(input("The Kinetic Energy of the ball with a mass of 10 at 100 MPH is:")) v=0 print("Mass", " ", "Velocity to reach",KE ) for mass in range(140, 321, 15): v = math.sqrt((2*KE)/mass)) # no need for * (1/mass), just divide mass += 15 print (mass," ", v)

请注意，如果您希望用户为input()变量提供mass，则需要相应地更改循环。

寻找速度（Pythin，空闲）

1 个答案: