How do I find the mass of a block on an inclined plane?
I have been given the force necessary to cause the block to have an impending motion up the inclined plane which is 100 N. The angle of inclination is 30 degrees and μ = 0.28. How do I find the mass of the block?
- Steve4PhysicsLv 71 month agoFavorite Answer
Because motion is ‘impending’ upwards (about to slide uphill) limiting frictional force acts downhill:
Fr = μR = μmgcos(30º) = 0.28*9.81*0.866m = 2.379m
The net force is zero as the block has zero acceleration. So the forces parallel to the incline are balanced:
downhill force = uphill force
mgsin(30º) + 2.379m = 100
m(gsin(30º) + 2.379) = 100
m (9.81*0.5 + 2.379) = 100
m = 100/(4.905 + 2.379)
. . = 13.7kg
You may be expected to round to 2 sig. figs., giving 14kg