Appreciate if someone could take the time to look at the following problem, my answers, and can point out where I have went wrong. Also, part 4, I think more info. is needed to determine this, but I may be wrong. Anyway, here goes:(adsbygoogle = window.adsbygoogle || []).push({});

A hoist motor is attached to a support beam as shown in the diagram. The hoist lifts a load of 3.5kg, the load starts from rest and has a final velocity of 2 m/s after 4 seconds. The motor can develop a torque of 4 Nm.

Determine:

i) The linear acceleration of the mass

ii) The angular acceleration of the motor

iii) The force on the beam at M when the hois is lifting the load

iv) The reaction forces RA and RB on the beam supports A and B

My attempt at solutions:

i) Linear acceleration (a) = (final velocity - initial velocity) / time

= (2 - 0)/4

= 0.5 m/s/s

ii) Work done in 4 seconds = 0.5mv^2

= 0.5 * 3.5 * 2^2

= 7 Joules

Angle of rotation = Work / Torque

= 7/4

= 1.75 radians in 4 seconds

Angular acceleration = 0.4375 radians/s/s

iii) Force = mass * acceleration = 3.5 * (9.81 + 0.5)

= 36.085 N

iv) Don't know how to tackle this part as it is.

Sketch can be found here

http://img443.imageshack.us/img443/5980/q2mplg7.jpg [Broken]

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# Homework Help: Motion & Beams Problem

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