A 3 m lever has its pivot point at 2 m from the right, what load must be applied to balance the lever with a mass of 400 N on the left side?
Refer to figure.
In order to achieve equilibrium, the moments of both sides of the pivot have to be equal:
- Moment = Mass x Arm
Therefore, we need to find out the missing moment and calculate the load in order to find the load needed to be applied for equilibrium.
The question is giving you the mass of 400 N at the short end of the lever, which is 1 m from the pivot point, giving:
- Moment = 400 N x 1 m = 400 Nm
Knowing the moment, we can now derive the load needed to be applied on the shorter end of the plank.
- Moment = Mass x Arm
- Mass = Moment / Arm = 400 Nm / 2 m = 200 N
NOTE:
The correct units must be used in order to have the correct calculation done.
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