Anonymous
Anonymous asked in Science & MathematicsPhysics · 1 month ago

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? 

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  • 1 month ago
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    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

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