Box on table has friction 
coefficient of friction = uk 
Fnet = ma
make clockwise +
 
Mg - ukmg= (m + M)a
 
g(M-μkm) = a
(M+m)
 
Tension force in rope?
 
Rule  - One rope, one tension
make clockwise +
Fnet = ma
 
T  - ukmg = ma
 
T  = ma + f
 
T  = ma + umg
 
 
Draw freebody diagram for M
 
SFy=-Ma
 
Tf - Mg = -Ma 
 
Draw free body diagram for m
 
 
Find sum of forces on m

Massless, frictionless pulley and ramp
Find acceleration of red box up the ramp (M)

 
 
Masses move together with one accel.
make CCW +
 
Fnet = ma
 
 
mg - Mgsinq = (m + M)a
Hanging weight force - friction = ma

 

(m - Msinq)g = a
(M + m)

 

When does a = 0?

 

Msinq = m

When does box move down ramp?

(m - Msinq)g = a
(M + m)

When mg greater than MsinӨ>m

 

©Tony Mangiacapre., St. Mary's H.S., Manhasset, NY
All Rights Reserved [Home] Established 1995