Pass two values from user input to a function and get result

Question

I have been given instructions to "write a program that asks the user to enter values for mass and velocity, and then calls the kinetic_energy function to get the object's kinetic energy."

I have written code that is logically correct but I am wondering if I have the syntax backwards then what is described in the instructions. I believe my main function is calculating the result and simply passing it to the kinetic_energy function. I believe the instructions are asking for it to be done in the reverse order. If my assumption is correct how would I rewrite it to comply with the instructions?

#Gets the inputs from the user for mass and velocity
def main():
    mass = int(input('Please enter the objects mass in kilograms: '))
    velocity = int(input('Please enter the objects velocity in meters per second: '))

#Calculates the kinetic energy
    kinetic_energy(ke = .5 * mass * velocity ** 2)

#Calculates the kinetic energy
def kinetic_energy(ke):
    print ('The amount of kenetic energy is ',format(ke,',.2f'),sep='')

main()

Answer 1

Typically you write functions that do "work".

So if you have a kinetic_energy function, you wnat that function to do some more work than just printing.

So, it'd be more appropriate to rewrite your stuff as:

#Gets the inputs from the user for mass and velocity
def main():
    mass = int(input('Please enter the objects mass in kilograms: '))
    velocity = int(input('Please enter the objects velocity in meters per second: '))

#Calculates the kinetic energy
    kinetic_energy(mass, velocity)

#Calculates the kinetic energy
def kinetic_energy(mass, velocity):
    ke = .5 * mass * velocity ** 2
    print ('The amount of kenetic energy is ',format(ke,',.2f'),sep='')

main()

Answer 2

You define kinetic_energy as a function that takes two arguments, mass and velocity, then returns the computed value:

def kinetic_energy(m, v):
    return .5 * m * v ** 2

Then you call the function from main:

def main():
    mass = int(input('Mass in kilograms: '))
    velocity = int(input('Velocity in m/s: '))
    ke = kinetic_energy(mass, velocity)
    print('Kinetic energy is {.2f}'.format(ke))

main()