1. A boy in a pedal car is moving at a speed of 1.40 m/s at...

1. A boy in a pedal car is moving at a speed of 1.40 m/s at the start of a 2.10 m high and 12.4 m long incline. The total mass is 54.5 kg, air resistance and rolling resistance can be modeled as a constant friction force of 41.0 N, and the speed at the lower end of the incline is 6.80 m/s. Determine the work done (in J) by the boy as the car travels down the incline.

2. An energy-efficient lightbulb, taking in 24.0 W of power, can produce the same level of brightness as a conventional lightbulb operating at power 100 W. The lifetime of the energy-efficient bulb is 10 000 h and its purchase price is $4.60, whereas the conventional bulb has lifetime 750 h and costs $0.46 per bulb. Determine the total savings obtained by using one energy-efficient bulb over its lifetime as opposed to using conventional bulbs over the same time period. Assume an energy cost of $0.20 per kilowatt-hour.

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genius_generous answered 2 years ago

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