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Questions and Answers
What happens to the speed of a falling object at the beginning of its fall?
What happens to the speed of a falling object at the beginning of its fall?
A feather and a coin will fall at the same speed once air resistance equals their weights.
A feather and a coin will fall at the same speed once air resistance equals their weights.
False (B)
What is terminal velocity?
What is terminal velocity?
Terminal velocity is the steady speed an object reaches when the force of air resistance equals the force of gravity.
When a falling object experiences terminal velocity, the resultant force acting on it is _____ .
When a falling object experiences terminal velocity, the resultant force acting on it is _____ .
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Match the following stages of falling objects with their descriptions:
Match the following stages of falling objects with their descriptions:
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Which of the following motions can a soft rubber ball undergo when acted upon by forces?
Which of the following motions can a soft rubber ball undergo when acted upon by forces?
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A rigid body in uniform motion will change its state of motion if the resultant force applied on it is zero.
A rigid body in uniform motion will change its state of motion if the resultant force applied on it is zero.
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What is the special force called that balances the resultant force acting on a body?
What is the special force called that balances the resultant force acting on a body?
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A branch of mechanics that studies forces in equilibrium is called ______.
A branch of mechanics that studies forces in equilibrium is called ______.
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Match the following terms with their definitions:
Match the following terms with their definitions:
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What must be true for a body to be in equilibrium?
What must be true for a body to be in equilibrium?
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A non-rigid body cannot execute vibrational motion when acted upon by a couple of forces.
A non-rigid body cannot execute vibrational motion when acted upon by a couple of forces.
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What is the turning effect of a force called?
What is the turning effect of a force called?
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The unit of moment of force is expressed in joules.
The unit of moment of force is expressed in joules.
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What is the formula for calculating the moment of couple?
What is the formula for calculating the moment of couple?
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The moment of a force brings about _____ or _____ rotation of the body.
The moment of a force brings about _____ or _____ rotation of the body.
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Which of the following represents the torque applied if two forces of 20 N each act on a steering wheel with a diameter of 40 cm?
Which of the following represents the torque applied if two forces of 20 N each act on a steering wheel with a diameter of 40 cm?
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When a body is in equilibrium, the total counter clockwise moment is less than the total clockwise moment.
When a body is in equilibrium, the total counter clockwise moment is less than the total clockwise moment.
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Describe the principle of moments in your own words.
Describe the principle of moments in your own words.
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The perpendicular distance between the forces in a moment of couple is represented as _____ (use symbol).
The perpendicular distance between the forces in a moment of couple is represented as _____ (use symbol).
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What did Aristotle believe about the speed of falling objects?
What did Aristotle believe about the speed of falling objects?
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Galileo Galilei proved that all objects fall at the same rate regardless of mass.
Galileo Galilei proved that all objects fall at the same rate regardless of mass.
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Define torque of a couple.
Define torque of a couple.
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The force that causes objects to fall is called _____ .
The force that causes objects to fall is called _____ .
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Match the scientists with their contributions to the understanding of falling objects:
Match the scientists with their contributions to the understanding of falling objects:
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What happens to a free falling object as it continues to fall?
What happens to a free falling object as it continues to fall?
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Air resistance acts in the same direction as the weight of an object.
Air resistance acts in the same direction as the weight of an object.
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The weight of an object acts _____ .
The weight of an object acts _____ .
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Name one factor that affects the terminal velocity of a falling object.
Name one factor that affects the terminal velocity of a falling object.
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Which of the following is NOT a characteristic of a free falling object?
Which of the following is NOT a characteristic of a free falling object?
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In a state of equilibrium, what is true about the total moments?
In a state of equilibrium, what is true about the total moments?
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The equation F1 x d1 = F2 x d2 is applicable only when there are more than two forces acting on the lever.
The equation F1 x d1 = F2 x d2 is applicable only when there are more than two forces acting on the lever.
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What equipment is needed to verify the principle of moments as mentioned?
What equipment is needed to verify the principle of moments as mentioned?
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In Figure 1.15, the equation for total moments is F1 x d1 = (F2 x d2) + (F3 x ______).
In Figure 1.15, the equation for total moments is F1 x d1 = (F2 x d2) + (F3 x ______).
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Match the following forces with their respective moments:
Match the following forces with their respective moments:
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What must be done to achieve equilibrium during the experiment?
What must be done to achieve equilibrium during the experiment?
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To ensure a ruler is perfectly horizontal, both weights must be equal.
To ensure a ruler is perfectly horizontal, both weights must be equal.
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What is the next step after recording the weights in Activity 1.3?
What is the next step after recording the weights in Activity 1.3?
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In equilibrium, the moment of force in clockwise direction must equal the moment of force in ______.
In equilibrium, the moment of force in clockwise direction must equal the moment of force in ______.
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What equation represents the balance of moments in the case of two forces acting on a lever?
What equation represents the balance of moments in the case of two forces acting on a lever?
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Study Notes
Moment of Force
- Learning Objectives: Describe statics, equilibrium, resultant, moment and parallelogram law of forces, couple, torque, and principle of moments.
- Forces and Equilibrium: The motion of a single point in a body can be described with translational motion. A body can also rotate or vibrate. A rigid body's shape and size remain consistent when acted upon.
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Resultant Force:
- Forces along the same line and direction add to a resultant force. The body moves in the direction of the greater force.
- When equal forces act in opposite directions, the resultant force is the difference in magnitude. The body moves in the direction of the greater force.
Couple
- Definition: A pair of equal and parallel forces acting in opposite directions.
- Effect: Creates a turning effect (moment of couple or torque).
- Mathematical Formula: Moment of couple (τ) = Force (F) x Perpendicular distance (d) between forces (Nm).
Principle of Moments
- Definition: The total counter-clockwise moment equals the total clockwise moment for a body in equilibrium.
- Formula: Total Counter Clockwise Moments = Total Clockwise Moments
Falling Objects
- Learning Objectives: Explain forces changing with velocity, terminal velocity.
- Force on Falling Objects: Objects accelerate due to gravity, but air resistance also opposes the motion. The weight is a force downwards, while the air resistance is upwards. Terminal velocity is the constant speed attained when air resistance equals gravity.
- Free Falling Objects: Objects in free fall experience only gravity. Accelerate downwards at 9.8 m/s^2.
- Drag Force: Air resistance increasing with an object's speed. Depends on velocity, surface area, air density, and object shape.
- Terminal Velocity: The constant speed reached when an object falls vertically, occurring when air resistance opposing gravity equals the object's weight.
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Stages of Falling Objects:
- Initial acceleration downwards due to gravity.
- Increasing air resistance with increased speed;
- Air resistance eventually balances the object's weight, resulting in constant terminal velocity.
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Description
This quiz covers the concepts of statics and equilibrium, focusing on the moment of force, resultant forces, and the principle of moments. You'll explore the effects of couples and torque, alongside their mathematical applications. Test your understanding of these fundamental principles in mechanics.
