Angle in degrees btwn f1 and f2

[hatrk219]

A force, f1, of 5 N acts in a direction 53.1° counter clockwise from the x-axis. A second force, f2, is given by f2 = 6i-3j N. What is the angle in degrees between f1 and f2? thanks!

 

[Hootenanny]

A force, f1, of 5 N acts in a direction 53.1° counter clockwise from the x-axis. A second force, f2, is given by f2 = 6i-3j N. What is the angle in degrees between f1 and f2? thanks!

Hi hatrk219 and welcome to PF,

We don't just dole out answers here, we'll help you along the way, but you have to do some work yourself. How do you think you should approach the question?

 

[HallsofIvy]

I can think of two ways to do that:

1) Write f1, which is given in terms of length and direction, in terms of components and use the dot product, or

2) Write f2, which is given in terms of components, in terms of length and direction, and subtract the angles.