A 2.5-kg book rests on a surface inclined at 25 friction are 0.55 and 0.35, resp
ID: 2304941 • Letter: A
Question
A 2.5-kg book rests on a surface inclined at 25 friction are 0.55 and 0.35, respectively. 20. Find the normal force exerted on the book A) 22.2N B)33.5N C)41.1N D) ebove the horizontal. The coficients of static and kinetice N C)41.IN D)594N E)65.S N F)70.0 N 21. Find the magnitude of friction force between the book and the surface. A) 83.6N B)9.19N C) 10.7N D) 11.4N E) 12.2N F) 13.0N 22. The incline angle is now increased. At what angle does the book start to slide? C)59.8" D) 42.7" E)30.1° F)28.8° A) 85.5° B) 63.0°Explanation / Answer
a)
Normal Force
N=mgCos25 =2.5*9.81*Cos25
N=22.2 N
b)
Frictional force
Ff =usN =0.55*22.2
Ff = 12.2 N
c)
For book to slide
usmgCos(o)=mgsino
o=tan-1(us) =tan-1(0.55)
o=28.8o