Balanced bodies have balanced moments
This classroom worksheet gives KS4 physics or combined science students practice with balanced moments.
There are four diagrams, using two objects on a pivoted beam for students to find the missing value of distance or force.
The resource also includes a longer challenge question that uses three objects to find the missing mass (rather than force), requiring the separate calculation of weight (using an equation that they should be able to recall). The challenge question also includes a significant figure requirement.
An extract from the resource:
If an object balances, the total clockwise moment about a pivot equals the total anticlockwise moment about it.
You should be able to calculate the size of a force, or its distance from a pivot, acting on an object that is balanced.
Calculate the size of the unknown force or unknown distance in the examples below. Show your full working.
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Challenge question 2.00 kg and 5.00 kg masses are each positioned on a 2.00 m long beam, pivoted at its centre. The 2.00 kg mass is 90 cm from the pivot; the 5.00 kg mass is 35 cm from the pivot. |
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Perform calculations to find the weight of a toy car balancing the beam, 86 cm on the other side of the pivot. Give your answer to 3 significant figures. Take the strength of gravity to be 9.81 N/kg. |
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