You are provided with a metre rule, a weight hanger, slotted masses, M, a piece (if string, a weighing balance and a knife edge. Use the diagram above as a guide to perform the experiment.
(i) Using the weighing balance, determine and record the mass, M\(_{o}\), of the unloaded metre rule.
(ii) Determine and record the mass, m, of the weight hanger.
(ii) Suspend the metre rule horizontally on the knife edge. Adjust the knife edge to a point G on the metre rule where it balances horizontally.
(iv) Record the distance, d = AG.
(v) Suspend the weight hanger securely at a point, P, on the metre rule such that AP= 5 cm. Keep the hanger at this point throughout the experiment
(vi) Add a mass, M = 20 g to the hanger, adjust the knife edge to a point K on the metre rule such that it balances horizontally as shown in the diagram above.
(vii) Determine and record the distance z = AK.
(vii) Record M and evaluate y – (z – 5), x – (d – z] and v = \(\frac{x}{y}\)
(ix) Repeat the experiment for M = 40 g, 60 g, 80 g and 100 g. In each case, evaluate y, x and v.
(x) Tabulate the results.
(xi) Plot a graph with M on the vertical axis and v on the horizontal axis, sinning both axes from the origin (0,0).
(xii) Determine the slope, s, of the graph.
(xii) Determine the intercept, c, on the vertical axis.
(xiv) State two precautions taken to ensure accurate results.
(b) (i) Under what condition is an object said to be in a stable equilibrium
(ii) Auniform beam of weight 50 N has a body of weight 100 N hung at one end of it. If the beam is 12 m long, determine the distance of a support from a 100 N body for it to balance horizontally.
Explanation
(a) OBSERVATIONS
(i) Value of M\(_{0}\) correctly determined and recorded to at least 1 d.p in grammes
(ii) Value of m correctly determined and recorded to at least 1 d.p in grammes
(iii) Value of d correctly read and recorded to at least 1 d.p in cm
(iv) Five values of M correctly recorded in grammes
(v) Five values of Z = AK correctly read and recorded to at least1 d.p in cm and in trend.
Trend: As M increases Z decreases.
(vi) Five values of y = (Z - 5) correctly evaluated and recorded.
(vii) Five values of x = (d - Z) correctly evaluated and recorded
(vii) Five values of v = \(\frac{x}{y}\) correctly evaluated and recorded to at least 3 d.p
(ix) Composite table showing at least M, Z,y, x and v.
(b)(i) Condition for a body to be in stable
- The algebraic sum of all external forces on the object is zero
OR
- The algebraic sum of all external torques from the external forces acting on the object is zero.
OR
- The sum of clockwise moments about a point in the object is equal to the sum of anticlockwise moment about the same point.
OR
- The algebraic sum of all moments about a point on the object is zero.
(ii) If the distance is y,
100y = 50(6 - y)
100y = 300 - 50y
150y = 300
y = 2m