A block of mass m slides down an incline of mass M. As shown, th acceleration of the block is a. The coefficient of kinetic friction between the block and the incline is ì1, while the coefficient of kinetic friction between the incline and ground is ì2. If the incline stays motionless all the time, what is the friction f between incline and ground, and what is the normal force N vertically acting on the ground?
Select one:
a. f = (M+m)gì2 N = (M + m)g - ma sinè
b. f = mg(cos è - sin è)cosè N = (M + m)g - ma cosè
c. f = macos è N =Mg + mg cos è (cos è + ì1sin è)
d. f = mg ì1cos è N= (M + m)g
e. f = Mgì2 N = Mg
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