Questions and Answers
What is the equation used to calculate distance when initial velocity equals zero and acceleration is due to gravity?
s = \frac{g}{2}t^{2}
What is the significance of the slope in the equation of the line y = mx + c when c = 0?
Parallax error can be avoided when measuring distance in the experiment.
False
Which of the following is NOT a precaution to take during the experiment?
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Why should different masses of spheres be used in the experiment?
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What is mass?
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Mass is a vector quantity.
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What is momentum?
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What is the SI unit of force?
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Which of the following is not one of Newton's laws of motion?
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What is the formula for calculating weight?
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What happens when air resistance equals gravitational force?
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What is the reaction force acting on an object at rest on a surface?
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Friction opposes the motion of a ___
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What is the relationship between the weight of an object and the planet's mass?
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What does Newton's second law state?
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What is mass a measure of?
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What is the SI unit of momentum?
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According to the conservation of momentum, what is true before and after an interaction?
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What is the velocity of the green puck after the collision?
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What is the change in momentum of the red puck?
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What is the formula that describes weight?
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Newton's first law states that a body remains at rest unless acted upon by an external force.
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The force of attraction between two point masses is inversely proportional to the product of their masses.
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What unit is defined so that 1 N is the force that causes a body of mass 1 kg to accelerate by 1 m s-2?
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What happens when upward air resistance equals downward gravitational force?
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What does the normal reaction force act on?
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The formula for force is F = _____
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What is the acceleration of a sled of mass 60 kg pulled by a force of 500 N with a resistance of 80 N?
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What is the slope of the graph plotting distance against time squared used to calculate?
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Study Notes
Mass and Momentum
- Mass (m) measures the amount of matter in an object and is a scalar quantity with the SI unit of kilogram (kg).
- Momentum (p) is the product of mass and velocity, expressed as p = mass × velocity. It is a vector quantity with the SI unit kilogram metre per second (kg m s⁻¹).
- In a closed system, total momentum before an interaction equals total momentum after.
Sample Problem: Hockey Pucks Collision
- Two identical pucks collide: the red puck moves at 5 m s⁻¹ to the right; the green puck moves at 2 m s⁻¹ to the left.
- After collision, the red puck comes to rest.
- Use conservation of momentum to determine the green puck's velocity and each puck's change in momentum.
Force and Newton's Laws
- Force (F) is defined as that which can cause acceleration, a vector quantity measured in newtons (N).
- 1 N equals the force needed to accelerate a 1 kg mass by 1 m s².
- Newton's Laws:
- Law 1: An object at rest stays at rest, and an object in motion continues at constant velocity unless acted on by an external force.
- Law 2: The change in momentum is proportional to the applied force and in the direction of that force.
- Law 3: For every action, there is an equal and opposite reaction.
Weight and Forces in Fluids
- Weight (W) equals mass times the gravitational acceleration, making it a vector quantity measured in newtons.
- In fluids, objects face air resistance, a frictional force that increases with velocity. Terminal velocity occurs when this force equals gravitational force, resulting in constant speed.
Centre of Gravity and Gravity Variations
- Centre of gravity is where an object's weight appears to act.
- Acceleration due to gravity (g) varies with location due to Earth's shape (not perfectly spherical) and topographical differences like mountains and valleys.
Friction
- Friction (Fₓ) is a force opposing motion, influenced by surfaces' nature and the weight of the object.
- It allows vehicles and pedestrians to accelerate by providing grip.
Sample Problem: Sled on Snow
- A sled with a mass of 60 kg is pulled with a force of 500 N against a frictional resistance of 80 N.
- Resultant force can be calculated as tractive force minus friction.
- Acceleration can be calculated using the standard force equation.
Normal Reaction Forces
- Normal reaction force acts perpendicular to a surface, equal in magnitude and opposite in direction to an object's weight.
Experimental Procedures and Conclusions
- Experimental setups often involve measuring forces, masses, and accelerations to confirm principles like Newton’s laws and momentum conservation.
- Data is recorded and graphed to derive relationships, such as force versus acceleration, revealing that force is proportional to acceleration based on Newton's second law.
Precautions and Alternative Methods
- Ensure accurate measurements and minimize friction for more reliable results.
- Alternative methods using different equipment (e.g., air track, light gates) can yield similar findings and confirm physics principles consistently.
Conclusion
- Fundamental physics principles including mass, momentum, force, weight, air resistance, and gravity underlie various phenomena and can be tested through systematic experimentation and calculations.
Mass and Momentum
- Mass (m) measures the amount of matter in a body, represented as a scalar quantity in kilograms (kg).
- Momentum (p) is the product of mass and velocity (p = m × v), a vector quantity measured in kilograms metre per second (kg m/s).
- Conservation of momentum states that total momentum in a closed system before and after an interaction remains constant.
- Example shown with two colliding hockey pucks demonstrates conservation; the red puck stops, resulting in the green puck moving right at 3 m/s after collision.
Force and Newton's Laws
- Force (F) causes acceleration, defined as a vector quantity in newtons (N), where 1 N = 1 kg m/s².
- Newton's laws of motion:
- Law 1: An object remains at rest or in uniform motion unless acted upon by an external force. Example: Seat belts prevent passengers from continuing at constant velocity in a crash.
- Law 2: Rate of change of momentum is proportional to applied force, acting in the same direction. Example: Kicking a football applies force, resulting in acceleration.
- Law 3: For every action, there is an equal and opposite reaction. Example: Rockets propel forward by expelling gas backward.
Gravitational Force
- The gravitational force between two masses is proportional to their mass and inversely related to the distance squared (F ∝ 1/d²).
- Earth's gravity sustains its atmosphere; insufficient mass (like the Moon) leads to no atmosphere.
- Weight (W) is mass multiplied by gravitational acceleration (W = m × g); it is also a vector quantity measured in newtons.
Motion and Friction
- Air resistance, increasing with velocity, acts against a moving object. Terminal velocity occurs when upward air resistance equals downward gravitational force.
- Friction (Ff) opposes motion, its strength influenced by surface types and object weight; essential for grip in vehicles and shoes.
- Sample problem with sled: A 60 kg sled experiences a resultant force of 420 N and an acceleration of 7 m/s².
Normal Reaction Force
- An object on a surface exerts a normal reaction force (N) perpendicular to the surface, equal in magnitude and opposite in direction to the object's weight.
Experimental Procedures and Data Handling
- Several experiments outlined include:
- Measuring the relationship between force and acceleration using a ticker tape and trolley system, demonstrating that force is proportional to acceleration.
- Using free-fall apparatus to calculate acceleration due to gravity by squaring time and plotting distance versus time squared, where gravitational acceleration is twice the slope of the graph.
- Precautions for experiments include reducing friction, ensuring proper apparatus alignment, and accounting for external factors to enhance accuracy.
Conclusion
- The experiments reinforce the foundational principles of mechanics, including momentum conservation, force interactions, and gravitational effects, with careful data collection and error reduction techniques emphasized for reliability.
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Description
Explore the fundamental concepts of mass and momentum in this physics quiz. Understand how mass is a scalar quantity measured in kilograms, and learn about momentum as a vector quantity calculated as mass times velocity. Test your knowledge on these key principles of physics.