Lito and Lando pull 2 ropes attached to a cabinet with forces 80 N and 120 N. What is the resultant force if they pull at right angle to each other?

1 Answer
Jul 13, 2018

144.22N (2dp)


Forces are vector quantities and must be added as vectors.

Vectors at right angle to each other can be added using Pythagoras to calculate the magnitude of the resultant force. (This does not give the angle of the resultant).

#(F_R)^2 = (F_1)^2 + (F_2)^2#

#(F_R)^2 = (80)^2 + (120)^2#

#(F_R)^2 = 20800#

#F_R = sqrt20800 = 144.22 (2dp)# Newtons

Don't forget to put the units (N) in your answer.

You can get the angle of this force relative to the applied force by using inverse cosine.

e.g. #cos theta = 80/144.22# for angle from the 80N force