Physics WAEC

Equilibrium Of Forces

Gbogbo ọrọ náà

In the realm of physics, equilibrium plays a fundamental role in comprehending the delicate balance of forces acting on a body. Equilibrium is a state where the forces and torques acting on an object are balanced, resulting in no linear or angular acceleration. By studying equilibrium, we delve into the intricate interplay between various forces that keep objects stationary or in uniform motion.


Analyzing Stable, Unstable, and Neutral Equilibrium:

One of the key objectives of this course material is to grasp the concept of stability in equilibrium. Objects can exhibit stable, unstable, or neutral equilibrium based on the behavior of forces acting upon them. Understanding these different types of equilibrium is crucial in predicting the response of objects to external disturbances and ensuring their stability.

Principles of Moments in Equilibrium:

The application of the principle of moments is central to determining the equilibrium of forces acting on a body. By analyzing the torques produced by these forces, we can ascertain the conditions under which a body remains in equilibrium. This principle provides a powerful tool for solving complex problems involving the balancing of forces in various systems.

Resolution and Composition of Forces:

To gain a deeper insight into equilibrium, we explore the concepts of resolution and composition of forces through practical force board experiments. By breaking down forces into their components and then combining them, we can determine the resultant and equilibrant forces present in a system. This hands-on approach enhances our understanding of how forces interact to maintain equilibrium.

Utilizing Triangle and Parallelogram of Forces:

The triangle and parallelogram of forces are invaluable tools for visualizing and calculating resultant and equilibrant forces in different directions. By applying these geometric methods, we can effectively determine the net force acting on a body and ensure that equilibrium is maintained. Experimentally exploring these concepts brings clarity to the principles governing equilibrium in physics.

Conclusion:

Equilibrium of forces serves as a cornerstone in the study of physics, providing a framework to analyze the balance of forces in diverse physical systems. Through practical experiments and theoretical understanding, we can unravel the complexities of equilibrium and apply this knowledge to solve real-world problems. By mastering the principles outlined in this course material, students will develop a solid foundation in handling forces and achieving stability in various scenarios.

Ebumnobi

  1. Utilize the triangle and parallelogram of forces to determine resultant and equilibrant forces
  2. Apply the principles of moments to determine equilibrium of forces acting on a body
  3. Analyze the conditions for stable, unstable, and neutral equilibrium in rigid bodies
  4. Understand the concept of equilibrium in physics
  5. Demonstrate the resolution and composition of forces using force board experiments

Akwụkwọ Ọmụmụ

Avaliableghị

Nnyocha Ọmụmụ

Ekele diri gi maka imecha ihe karịrị na Equilibrium Of Forces. Ugbu a na ị na-enyochakwa isi echiche na echiche ndị dị mkpa, ọ bụ oge iji nwalee ihe ị ma. Ngwa a na-enye ụdị ajụjụ ọmụmụ dị iche iche emebere iji kwado nghọta gị wee nyere gị aka ịmata otú ị ghọtara ihe ndị a kụziri.

Ị ga-ahụ ngwakọta nke ụdị ajụjụ dị iche iche, gụnyere ajụjụ chọrọ ịhọrọ otu n’ime ọtụtụ azịza, ajụjụ chọrọ mkpirisi azịza, na ajụjụ ede ede. A na-arụpụta ajụjụ ọ bụla nke ọma iji nwalee akụkụ dị iche iche nke ihe ọmụma gị na nkà nke ịtụgharị uche.

Jiri akụkụ a nke nyocha ka ohere iji kụziere ihe ị matara banyere isiokwu ahụ ma chọpụta ebe ọ bụla ị nwere ike ịchọ ọmụmụ ihe ọzọ. Ekwela ka nsogbu ọ bụla ị na-eche ihu mee ka ị daa mba; kama, lee ha anya dị ka ohere maka ịzụlite onwe gị na imeziwanye.

  1. A block is at rest on an inclined plane. What prevents the block from sliding down the plane? A. Normal force B. Tension force C. Frictional force D. Gravitational force Answer: A. Normal force
  2. In which of the following situations is the equilibrium of forces unstable? A. A book resting on a table B. A ball hanging from a string C. A pencil standing on its tip D. A car parked on a flat road Answer: C. A pencil standing on its tip
  3. What is the condition for equilibrium of parallel forces acting on a rigid body? A. The sum of clockwise moments equals the sum of counter-clockwise moments B. The sum of forces is zero C. The sum of forces equals the mass times acceleration D. The sum of moments is zero Answer: A. The sum of clockwise moments equals the sum of counter-clockwise moments
  4. When a body is in neutral equilibrium, what can be said about its potential energy? A. It is minimum B. It is maximum C. It is zero D. It is varying Answer: C. It is zero
  5. Which of the following tools can be used to determine the equilibrium of forces acting on a body experimentally? A. Loaded test-tube oscillating in a liquid B. Simple pendulum C. Force board D. Spiral spring Answer: C. Force board
  6. In the equilibrium of forces, the sum of all forces in any direction is equal to: A. The force of friction B. The weight of the body C. Zero D. The normal force Answer: C. Zero
  7. If a rigid body is under the action of non-parallel forces, what is a condition for equilibrium? A. The forces must have equal magnitudes B. The forces must be perpendicular to each other C. The lines of action of the forces must intersect D. The sum of the forces in any direction is zero Answer: D. The sum of the forces in any direction is zero
  8. When using the triangle of forces to determine resultant forces, what does the closing side of the triangle represent? A. Equilibrant force B. Net force C. Component force D. Applied force Answer: A. Equilibrant force
  9. Which type of equilibrium occurs when a small displacement from the equilibrium position results in an increasing restoring force? A. Stable equilibrium B. Unstable equilibrium C. Neutral equilibrium D. Dynamic equilibrium Answer: A. Stable equilibrium
  10. In the case of rotational equilibrium, what must be true about the sum of all moments acting on the body? A. It must be zero B. It must be maximum C. It must be negative D. It must be positive Answer: A. It must be zero

Ajụjụ Nnyocha

Nna, you dey wonder how past questions for this topic be? Here be some questions about Equilibrium Of Forces from previous years.

Ajụjụ 1 Ripọtì

Which of the following is an example of a couple?
Akọwa Nkọwa
A couple is a pair of forces that are equal in magnitude but opposite in direction, and that are applied to a body at different points. The forces of a couple do not produce any translation, but they do produce a rotation.

Ajụjụ 1 Ripọtì

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.

Akọwa Nkọwa

(a) Results and graph

Mass of unloaded metre rule, \(M_0=75.0\text{ g}\).

Mass of weight hanger, \(m=20.0\text{ g}\).

Balance point of unloaded metre rule: \(d=AG=50.0\text{ cm}\).

For each load, \(y=z-5\), \(x=d-z\), and \(v=\dfrac{x}{y}\).

\(M\) (g)\(z=AK\) (cm)\(y=z-5\) (cm)\(x=d-z\) (cm)\(v=x/y\)
2034.329.315.70.536
4030.025.020.00.800
6026.821.823.21.064
8024.319.325.71.332
10022.317.327.71.601

The plotted graph of \(M\) against \(v\), with both axes beginning at the origin, is shown below.

graph
Graph of M against v. The straight line of best fit has gradient approximately 75 g and vertical intercept approximately -20 g.

Using two widely separated points on the line of best fit, \((v_1,M_1)=(0.536,20)\) and \((v_2,M_2)=(1.601,100)\):

\[s=\frac{M_2-M_1}{v_2-v_1}=\frac{100-20}{1.601-0.536}=75.1\text{ g}\approx75.0\text{ g}.\]

The vertical intercept is \(c\approx-20.0\text{ g}\).

Thus, within experimental accuracy, \(s=M_0\) and \(c=-m\).

Precautions

  1. The metre rule was allowed to come to rest and was balanced horizontally before each reading was taken.
  2. All scale readings were taken with the eye vertically above the mark to avoid parallax error.

(b)

(i) An object is in stable equilibrium if, when slightly displaced, its centre of gravity rises and a restoring moment acts to return it to its original position.

(ii) Let \(y\) be the distance of the support from the \(100\text{ N}\) body. Taking moments about the support:

\[100y=50(6-y)\]

\[100y=300-50y\]

\[150y=300\]

\[y=2.0\text{ m}.\]

Therefore, the support should be placed \(\boxed{2.0\text{ m}}\) from the \(100\text{ N}\) body.


Ajụjụ 1 Ripọtì

Two forces A and B act at a point. If their resultant is [given by] (B - A) in the direction of B, then