Question

two horses on opposite sides of a narrow stream are pulling a barge along the stream. Each horse pulls with a force of 720N. The ropes from the horses to a common point on the front of the barge from an angle of 60 degrees with each other. What is the resultant force exerted by the two horses?

Answer 1

Each horse's force forms a right angle triangle with the barge and subtends an angle of 60/2 = 30°. The resultant in the direction of the barge's motion is:
Fx = Fcos(∅)
We can multiply this by 2 to find the resultant of both horses.
Fx = 2Fcos(∅)
Fx = 2 x 720cos(30)
Fx = 1247 N