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Questions and Answers
What is the unit of force in the metric system?
What does density measure?
Which metric system uses centimeters, grams, and seconds as its basic units?
What is the relationship between meters and feet in terms of conversion?
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Which of the following statements is true regarding vector quantities?
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When converting units, what is the key to using the conversion factor correctly?
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What is the kinetic energy (K) of an object with a mass of 60 kg moving at a velocity of 8 m/s?
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At position 2, what is the value of kinetic energy (K) if an object's kinetic energy at position 1 was 1920 J?
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How high (h) can an object reach if 1920 J of energy can be converted into gravitational potential energy (U), assuming mass is 60 kg?
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What is the formula used to calculate power (P) in relation to work done (W) and time (Δt)?
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If a 193 kg curtain needs to be raised 7.5 m in 5 seconds, what is the required power output calculated as?
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Which motor is best suited for raising a 193 kg curtain 7.5 m in approximately 5 seconds?
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What is the acceleration of an object that changes its velocity from 0 m/s to 30 m/s in 4 seconds?
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If a football player applies a force of 1500 N to an opposing player with a mass of 100 kg, what is the acceleration of the opposing player?
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Which statement is true about an object moving at 40 m/s with no acting forces?
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What is the average force experienced by a 0.046 kg golf ball that accelerates to 67 m/s in 1 ms?
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According to Newton's third law of motion, what happens when one object exerts a force on another object?
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What force would be experienced by Al when he applies a force of 1500 N on Bob, assuming Bob has a mass of 100 kg?
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If Al has a mass of 75 kg and applies a force of 1500 N, what is his acceleration?
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Which of the following best describes the motion of an object under no external forces?
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What is the net force acting on a person standing in a lift accelerating downward at 0.45 m/s² if their mass is 85 kg?
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When the lift accelerates downwards, how does the force the person exerts on the floor of the lift compare to their weight?
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If a person of mass 94 kg stands in a lift accelerating upwards at 0.54 m/s², what is the correct method to calculate the force they exert on the floor?
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In the example of a tug boat towing a smaller boat, what is the total mass being accelerated if the tug boat is 8000 kg and the smaller boat is 2000 kg?
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Which formula represents the relationship between work, force, and distance?
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What is the SI unit of work?
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Why is work considered a scalar quantity?
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Which of the following actions constitutes performing work?
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What result is obtained when calculating the force exerted on the floor when a 65 kg person is in an upward accelerating lift at 0.6 m/s²?
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What happens to the force exerted on the lift floor when the lift accelerates upwards?
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Study Notes
Derived Units
- Speed is measured in meters per second (m/s), calculated as distance (m) divided by time (s).
- Acceleration is measured in meters per second squared (m/s²), which is the change in velocity (m/s) over time (s).
- Force is expressed in Newtons (N), defined as mass (kg) multiplied by acceleration (m/s²). One Newton equals one kilogram meter per second squared (1 N = 1 kg·m/s²).
- Density is defined as mass (kg) per volume (m³), expressed in kg/m³.
Unit Prefixes
- Unit prefixes denote powers of ten, each with a specific name and abbreviation.
- These prefixes can be universally applied to any basic units, acting as multipliers.
Other Unit Systems
- The Centimeter-Gram-Second (CGS) system uses centimeter, gram, and second as standard units for length, mass, and time.
- The British system, known as the foot-pound-second (FPS) system, uses feet for length, pounds for mass, and seconds for time; still in use in countries like the USA.
Unit Conversion
- Consistent units are crucial; conversions may be needed when units differ.
- Units can cancel each other out in calculations, similar to algebraic quantities.
- Example conversion factors include: 1 day = 24 hours, 1 hour = 60 minutes, 1 minute = 60 seconds.
- Converting feet to meters: 1 m = 3.281 ft can be used to convert distances accurately.
Scalars and Vectors
- Scalars are quantities described by a single number, like mass or temperature.
- Vectors include both magnitude and direction, represented in bold italicized type with an arrow.
- Equations are established to find acceleration (a = Δv/Δt) and force (F = ma).
Newton’s Laws of Motion
- Newton's Third Law states that for every action, there is an equal and opposite reaction; forces are mutual.
- Example: When a person kicks a wall, the wall exerts an equivalent force back, potentially causing injury.
Work and Energy
- Work (W) is dependent on force (F) and the distance (d) moved in the direction of the force; calculated as W = Fd.
- The SI unit for work is the Joule (J), equivalent to one Newton meter (N·m).
- Energy transformations are key to understanding mechanics; total energy before an event equals total energy after.
Power
- Power measures the rate at which work is done or energy is transformed, calculated as P = W/Δt.
- The unit of power is Watt (W), with 1 W being equivalent to 1 Joule per second (J/s).
- Other units include horsepower (hp), where 1 hp = 746 W.
Example Calculations
- Power required to lift objects can be calculated by evaluating force and the speed of operation, as demonstrated in various examples involving motors and lifting weights.
- Average forces can be derived from specific scenarios involving masses, forces, and resulting accelerations.
Important Examples
- A football player's force on an opponent can illustrate Newton's laws and the calculation of acceleration.
- Calculating work done on a backpack while climbing shows the relation between mass, height, and energy expended.
These notes summarize fundamental concepts and calculations related to physics, particularly focusing on units of measurement, mechanics, and energy dynamics.
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Description
This quiz covers essential concepts of derived units in physics, focusing on speed, acceleration, force, and density. Understand the relationships between these physical quantities and their formulae, including how they are derived and applied in various scenarios. Perfect for physics students looking to solidify their knowledge of unit measurements.
