A woman at an airport is towing her 20.0kg suitcase at

constant speed by pulling on a strap at an angle θ above the horizontal. She

pulls on the strap with a 35.0N force, and the friction force on the suitcase

is 20.0N. 

(i) Draw a free- body diagram of the suitcase. 

(ii) What angle does

the strap make with the horizontal? 

(iii)What is the magnitude of the normal force

that the ground exerts on the suitcase?