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Unformatted text preview: P = dW dt = F • v = T • ω power out power in e m = work out work in = Applications Applications 3 Applications Applications For Constant Power If P = constant , can combine with F = ma t 2 − t 1 = 1 P 1 2 mv 2 2 − 1 2 mv 1 2 adx = vdv x 2 − x 1 = 1 P 1 2 mv 2 3 − 1 2 mv 1 3 P = dW dt Example (prob. 4.3.23) • How fast can a 3200 lb car with a 200HP engine accelerate from 0 to 30 mph? (neglect drivetrain losses and air/ road drag) Constant Power Eqn 200 HP = 110,000 ftlb/s 30 mph = 44 ft/s 3200 lb 99.4 slugs True or False It is possible for power to be negative . 4 Example (prob. 4.3.4) Given: • h = 30 m • e m = 50% • Electricity costs $.15/kWhr Find: • Cost to pump 1000 liters Efficiency True or False It is possible for efficiency to be negative . Take Home Points • Power • Mechanical Efficiency e m = P = dW dt = F • v power out power in work out work in =...
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 Spring '06
 KAM
 Force, Mechanical Efficiency, (prob.

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