Physics help??

Question

A woman at an airport is towing her 15.0 kg suitcase at constant speed by pulling on the strap at an angle above the horizontal (Fig. P4.40). She pulls on the strap with a 24.0 N force, and the friction force on the suitcase is 10.0 N.

(a) What angle does the strap make with the horizontal?
65.37 degrees
(b) What normal force does the ground exert on the suitcase?
___?____

I already found the angle but how do I solve the 2nd part?? Thank you!

http://books.google.com/books?id=wDKD4IggBJ4C&pg=PA112&lpg=PA112&dq=fig+%22p4+40%22+college+physics&source=web&ots=fnlu-8GTUY&sig=mKHKkKuaFVoOM2kBNN8XHj_VY0k

This link has fig P4.40 on it.

Answer 1

Since the strap is at an angle of 65.37 degrees, the horizontal component of her 24N is
24cos(65.37)=10 N and the vertical component is
24sin(65.37) = 21.81 N
The acceleration of gravity on 15 kg is
F=ma=15*9.8=147 N so the total downwards force is
147 - 21.81 = 125.19 N
Since the suitcase isn't accelerating in the y direction, the -net- force must be 0 and the ground is exerting 125.19 N against the suitcase.

Doug