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This chapter explores the fundamental concepts of work, power, and simple machines. Students will engage in hands-on investigations involving measurement and calculations related to force, energy, and mechanical advantage through simple machines like pulleys and levers. Key topics include the definition of work, calculations of input/output work, efficiency, and the relationship between work and energy. This study aims to enhance comprehension of energy systems, emphasizing how machines affect the work done and the conservation of energy in various applications.
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Chapter 4 Physics A First Course Energy and Systems
Energy and SystemsMachines, Work, and Energy • 4.1 Work and Power • 4.2 Simple Machines • 4.3 Efficiency
Key Question: How do simple machines affect work? 4A Investigation: Force, Work, and Machines *Students read text section 4.1 AFTER Investigation 4A
4A Investigation Topics • Build and use a simple machine (ropes and pulleys). • Measure input and output forces in a simple machine. • Measure input and output distance in a simple machine. • Calculate mechanical advantage. • Calculate input and output work.
power watt horsepower Define work in terms of force and distance and in terms of energy. Calculate the work done when moving an object. Explain the relationship between work and power. Chapter 4.1 Objectives and Vocabulary
4.1 Work done against gravity mass (g) height object raised (m) W = mgh work (joules) gravity (m/sec2)
machine input output fulcrum simple machines mechanical advantage input arm output arm tension Describe how a machine woks in terms of input and output. Define simple machines and name some examples. Calculate the mechanical advantage of a simple machine given the input and output forces. Chapter 4.2 Objectives and Vocabulary
Key Question: How does a system get energy? 4B Investigation: Conservation of Energy *Students read text section 4.3 AFTER Investigation 4B
4B Investigation Topics • Measure the work done for a car on a track. • Graph forces versus distance for a car on a track. • Derive the formula for the speed of the car from force and mass data. • Predict the speed of the car given a force.
efficiency reversible irreversible Describe the relationship between work and energy in a simple machine. Use energy conservation to calculated input or output force or distance. Explain why a machine's input and output work can differ. Chapter 4.3 Objectives and Vocabulary