Questions and Answers
What is the rate at which work is done?
How much work is done to lift a 50kg barbell by 2m?
100J
Using a force to move an object through a distance is called what?
work
Is there work done on the wall?
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If the distance is 20m and the force is 5000N, how much work will be done?
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Mechanical energy combines what two types of energy?
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Kinetic energy is best described as what?
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What is the formula for gravitational potential energy at a specific height?
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What cliff should the rock be thrown from to give it the greatest gravitational potential energy?
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How much power is produced when using 160J of energy in 8 seconds?
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Simple machines can increase the amount of work done.
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What are the three classes of what?
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When potential energy is converted to kinetic energy, some energy leaves the system due to what?
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How much kinetic energy does a 2.0 kg ball have that is moving at 4 m/s?
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Reducing friction in a machine increases what?
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_____ is an example of a lever.
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What law states that the total sum of mechanical energy in a closed system remains constant?
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What is the ideal mechanical advantage (IMA) for a ramp that is 6m long and 2 m high?
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What is the AMA when the reel on a fishing rod uses 4N of forces to pull up a 24N fish?
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The tire on a bicycle is an example of what?
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Energy has the same unit as ___________, which is _____________.
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The percentage of input work that is converted into output work is called what?
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Study Notes
Power and Work
- Power is defined as the rate at which work is done.
- Work done on an object is the product of force and distance; for instance, lifting a 50kg barbell 2m results in 100 Joules (J) of work.
- Work is accomplished by applying a force to move an object over a certain distance.
Work and Force
- No work is done on a stationary wall, as there is no displacement.
- Calculating work: a force of 5000 Newtons (N) acting over a distance of 20 meters results in 100,000 Joules (J) of work.
Energy Types
- Mechanical energy is the sum of kinetic energy (energy of motion) and gravitational potential energy.
- Gravitational potential energy (PE) can be calculated using the formula PE = mgh, where m is mass, g is the acceleration due to gravity, and h is height.
- Kinetic energy (KE) can be calculated for a moving object; for a 2.0 kg ball at 4 m/s, KE equals 16 J.
Efficiency and Machines
- Simple machines do not increase the total amount of work done; rather, they make work easier.
- Efficiency refers to the percentage of input work converted to output work, impacting the performance of machines.
- Reducing friction in machines leads to increased efficiency.
Mechanical Systems
- In a closed system, the total sum of mechanical energy remains constant, as stated by the Law of Conservation of Energy.
- There are three classes of levers, which are tools that amplify force.
- An example of a lever is a mop, which can change the direction of applied force.
Inverted Mechanical Advantage
- The ideal mechanical advantage (IMA) for a ramp measuring 6m in length and 2m in height is 3.
- For a fishing rod's reel that uses 4 N of force to pull a 24 N fish, the actual mechanical advantage (AMA) is calculated to be 6.
Structural Components
- A tire is classified as a wheel and axle, demonstrating a simple machine.
- The unit of energy is the same as that of work, both measured in Joules.
Power Calculation
- Power output can be evaluated; using 160 Joules of energy in 8 seconds results in a power of 20 Watts (W).
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Test your knowledge on the concepts of work and power with these flashcards. Learn definitions, formulas, and practical applications related to force, distance, and energy. A great way to reinforce your understanding of physics principles.
