A student investigated the forces acting on a bracket.
The bracket of weight W was attached to a vertical wall with a hinge at point C. The bracket was held horizontally by a wire attached to the bracket at point A and to the wall at point B. The wire was at an angle θ to the bracket and exerted a force F on the bracket.
The student hung a mass from the bracket at a distance x from the hinge, as shown.
The student adjusted the position of the mass and measured x. For each value of x the student made corresponding measurements of F using a force meter.
The results are shown in the table.
x / cm | Mean F / N |
5 | 2 |
10 | 2.6 |
15 | 3.3 |
20 | 4.4 |
25 | 5.3 |
30 | 6.2 |
35 | 7 |
40 | 8.1 |
45 | 8.8 |
Criticise the recording of these results.
where
l is the length of the bracket
m is the mass hung from the bracket.
Determine a value for W using the graph.
θ = 42°
(3)
W = ................................ N
The student concluded that the value of g obtained is accurate.
Evaluate the student’s conclusion.
(2)
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