Net FOrce on an Object code Error.

Question

#A significant part of introductory physics is calculating the net force on an object based #on several different magnitudes and directions. If you're unfamiliar with how this works,
#Each force acting on the object is defined by its angle and magnitude. The process for #calculating net force is:
# - For each force, break the force into its horizontal and vertical components. The #horizontal component can be calculated as magnitude * cos(angle), and the vertical #component can be calculated as magnitude * sin(angle).
# - Sum all the horizontal components to find the total horizontal force, and sum the #vertical components to find the total vertical force.
# - Use the Pythagorean theorem to calculate the total magnitude: sqrt(total_horizontal #^ 2 + total_vertical ^ 2)
# - Use inverse tangent to calculate the angle: atan(total_vertical / total_horizontal)
#Write a function called find_net_force. find_net_force shouldtake one parameter as #input: #a list of 2-tuples. Each 2-tuple in the list is a (magnitude, angle) pair. angle will be in #degrees between -180 and 180.
#Return a 2-tuple containing the final magnitude and angle of all the forces. angle should #again be in degrees. You should round both magnitude and angle to one decimal place,
*****************************************************************************************************
from math import sin, cos, tan, asin, acos, atan, radians, degrees, sqrt
def find_net_force(force):
hor_comp = 0
vert_comp = 0
for tuple in force:
degre_radian = radians(tuple[1])
hor_comp = hor_comp + (tuple[0] * cos(degre_radian))
vert_comp = vert_comp + tuple[0] * sin(degre_radian)
mag = round((sqrt((hor_comp ** 2) + (vert_comp ** 2))) ,1)
angle = round(degrees(atan(vert_comp/hor_comp)),1)
return (mag, angle)
forces = [(10, 135), (10, -135), (20, 0), (20, 180)]
print(find_net_force(forces))
#The expected result is (14.1, 180.0) but my code is printing (14.1, -0.0)

Answer 1

You should use atan2 instead of atan in your angle calculation:

angle = round(degrees(atan2(vert_comp,hor_comp)),1)

Of course you'll need to import atan2 from math before you can use it :)