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# Equilibrium and Centre of Gravity Questions and Answers

Form 2 Physics Equilibrium and Centre of Gravity Questions and Answers

Lessons (**32**)

- 1.
What is meant by the centre of gravity of a body?

1m 34s - 2.
State two factors that should be controlled in manufacturing a cylindrical container of uniform thickness, which should normally be in a standing
position.

3m 10s - 3.
John carried a uniform post of mass 20kg horizontally on his shoulder as shown in fig.6. He placed the post on his shoulder such that the
centre of gravity of the pole is 1.0m behind him. He balanced the post by applying a downward force F at a point 0.5m on the part of the pole in front of him. Determine the value of the force F.

4m 2s - 4.
Figure 2 shows forces #F_1# and #F_2# acting on a metre rule such that it is in equilibrium. Mark on the figure a third force #F_3# acting on the rule
such that the equilibrium is maintained.

1m 38s - 5.
State how the position of the centre of gravity of a body in stable equilibrium changes to that in the rest position when the body is
slightly tilted and then released.

2m 29s - 6.
Figure 3 shows two identical hollow spheres. Sphere A is completely filled with the liquid while B is partially filled with identical liquid.
When the two spheres are rolled gently on a horizontal surface, it is observed that the sphere B stops earlier than the sphere A. Explain
this observation.

2m 1s - 7.
Figure 2 represents a rock balanced at point O. G is the centre of gravity of the rock. Use this information to answer questions 9 and 10.
Draw and label on the figure, the forces acting on the rock.

3m 4s - 8.
If the portion of the rock represented by the shaded part is chopped off, explain why the rock may topple to the right.

1m 54s - 9.
Figure 3 shows a rectangular block of wood with a hollow section (inside) at the position shown. The block is resting on a horizontal
bench.
(i) State the effect on the stability of the block when the hollow section is filled with water.
(ii) Explain your answer in (i) above.

1m 56s - 10.
Figure 3 shows a bimetallic strip with a wooden handle, suspended horizontally using a thin thread.
The strip is heated at the point shown. Explain why the system tips to the right.

2m 59s - 11.
Figure 5 shows a tor resting on top of a closed bottle. Use the information on the figure to answer questions 18 and 19.
Mark on the diagram, point Q, the approximate centre of gravity of the toy.

2m 5s - 12.
Giving a reason, name the state of equilibrium of the toy.

2m 1s - 13.
Figure 4 shows a uniform cardboard in the shape of parallelogram. Locate the centre of gravity of the cardboard.

0m 50s - 14.
Figure 3 shows a uniform meter rule pivoted at the 30cm mark. It is balanced by a weight of 2N suspended at the 5cm mark. Determine the weight of the
metre rule.

3m 12s - 15.
Figure 6 shows an athlete lifting weights while standing with the feet apart. Explain why standing with the feet apart improves the
athlete’s stability.

1m 40s - 16.
Figure 1 shows a lorry moving on an inclined section of a straight road. At the back is a chain hanging from a point on a horizontal axis through the centre of gravity of a lorry. State with a reason whether the lorry is stable or not stable.

1m 53s - 17.
State the reason why a steel sphere resting on a horizontal surface is said to be in neutral equilibrium.

1m 44s - 18.
A person carrying a heavy luggage using one hand leans away from the luggage. State the reason for this.

2m 27s - 19.
Figure 9 shows a uniform cardboard in the shape of parallelogram. Locate the centre of gravity of the cardboard.

2m 23s - 20.
Figure 1 shows a uniform wooden bar at equilibrium with two cans Y and Z of equal mass but different diameters.
The cans are simultaneously filled with equal volumes of water. Explain the observation made.

2m 26s - 21.
Figure 3 shows two possible designs of a three legged stool. State a reason why B is more stable than A.

2m 20s - 22.
Figure 7 shows an L-shaped wooden structure. On the diagram, construct appropriate lines to show the position of the centre of gravity for the structure.

3m 12s - 23.
A student carrying a heavy box using the right hand is observed to lean towards the left hand side. Explain this observation.

3m 0s - 24.
In the set up in fig. 3, the metre rule is in equilibrium. Given that the metre rule is uniform, determine its weight.

4m 42s - 25.
Figure 2 shows a beaker placed on a bench. A block of ice is placed in the beaker as shown. State and explain the change in the stability of the beaker when the ice melts.

2m 46s - 26.
Figure 7 shows a nonuniform log of mass 100kg balanced on the pivot by a 2kg mass placed as shown. Determine the distance of the centre of gravity of the log from the pivot.

4m 2s - 27.
Figure 3 shows two identical trolleys with loads A and B. the loads are identical in shape and size. Given that the density of A is greater than that of B, explain why the trolley in figure 3(ii) is more stable.

2m 56s - 28.
Figure 2 shows a solid cylinder standing on a horizontal surface. The cylinder is in stable equilibrium. On the horizontal space provided, sketch the cylinder in neutral equilibrium.

1m 47s - 29.
Figure 5 shows a uniform bar of length 1.0m pivoted near one end. The bar is kept in equilibrium by a spring balance as shown. Given that the reading of
the spring balance is 0.6 N, determine the weight of the bar.

3m 35s - 30.
(a) State the principle of moments.
(b) A uniform metal strip is 3.0cm wide, 0.6cm thick and 100cm long. The density of the metal is 2.7 #gcm^-3#.
(i) Determine the weight of the strip. The strip is placed on a pivot and kept in equilibrium by forces as shown in figure 13.
(ii) Determine the value of F and R.
(iii) X is the distance from the end of the plank to the point of application of force F.

16m 55s - 31.
Figure 12 shows a set up used to determine the mass of a solid S. the rod is pivoted at its centre of gravity C.
(i) State two measurements that need to be made to determine the mass of solid S.
(ii) Write an expression to show how the measurements in (i) above are used to obtain the mass of S.

3m 22s - 32.
Figure 6 shows two identical rods JK and LK connected with a hinge at K. The position of the centre of gravity for the system is at P. The arrangement is now adjusted so that J and L move equal distances towards O. Sketch the new arrangement on the same diagram and mark the new position of the centre of gravity.

3m 29s