work and energy
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The document discusses different types of work and power. It states that positive work is done when lifting a box, and negative work when lowering a box. Gravity does positive work when a box is lowered, and negative work when a box is raised. Power is defined as the rate of energy transfer, with the SI unit being watts and the US customary unit being horsepower.
work and energy
- 10. ? Man does positive work lifting box ? Man does negative work lowering box ? Gravity does positive work when box lowers ? Gravity does negative work when box is raised
- 18. ? Power is rate of energy transfer P ? W t SI units are Watts (W) m2 1 W 1 J / s 1 kg 3 s ? US Customary units are hp (horse power) 1 hp 550 ft lb/s 746 W