A student investigates the balancing of a metre rule.
Fig. 1.1 shows the arrangement.
The student places the metre rule on the pivot at the 50.0 cm mark. He places an object Q on the metre rule with its centre at the 90.0 cm mark. He places a load of weight P = 2.0 N on the metre rule and adjusts the position of the load so that the metre rule is as near as possible to being balanced.
He measures the distance x from the centre of the load to the pivot.
He repeats the procedure using loads of weight P = 3.0 N, 4.0 N, 5.0 N and 6.0 N. All the values of P and x are recorded in Table 1.1.
Calculate, and record in Table 1.1, the values of
Plot a graph of P / N (y-axis) against (x-axis). Start both axes at the origin (0,0).
In this experiment, xmax , the maximum possible value for x is 50.0cm. Calculate .
Use the graph to determine the minimum value of P required to balance the metre rule in this experiment. Show clearly on the graph how you determined this value.
minimum value of P = .....................................................
In this experiment, the width of object Q is slightly greater than the width of the metre rule. Explain briefly how you would place the object Q as accurately as possible on the 90.0 cm mark of the metre rule. You may draw a diagram.
Extended tier only
In this experiment, it is difficult to determine the exact position of the load that will make the metre rule balance.
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