In a bicycle race, a rider such as Lance Armstrong (mass = 70 kg) uses energy at a rate of 6.0 W/kg of body mass. If he travels at an average of 11.0 m/s in a 120 km race, how much energy does he expend?

What is the minimum energy needed to change the speed of a 1680 kg sports utility vehicle from 18.8 m/s to 44.2 m/s?

For saving energy, bicycling and walking are far more efficient means of transportation than is travel by automobile. For example, when riding at 11.5 mi/h, a cyclist uses food energy at a rate of about 430 kcal/h above what he would use if merely sitting still. (In exercise physiology, power is often measured in kcal/h rather than in watts. Here 1 kcal = 1 nutritionist's Calorie = 4186 J.) Walking at 3.00 mi/h requires about 250 kcal/h. It is interesting to compare these values with the energy consumption required for travel by car. Gasoline yields about 1.30 x 108 J/gal. (a) Find the fuel economy in equivalent miles per gallon for a person walking. mi/gal (b) Find the fuel economy in equivalent miles per gallon for a person bicycling. mi/gal

Suppose that in one year a country produces 2.77 × 10'' kilowatt-hours (kWh) of electrical energy from 4148 hydroelectric plants (1.00 kWh = 3.60 × 10° J). On average, each plant is 90.0% efficient at converting mechanical energy to electrical energy, and the average dam height is 50.0 m. At 2.77 x 10!1 kWh of electrical energy produced in one year, what is the average power output Payg per Pavg W %3D hydroelectric plant? What total mass of water m flowed over the dams during that year? m = kg What was the average mass of water mavg per dam that provided the mechanical energy to generate the electricity? mavg kg What was the average volume of water Vavg per dam that provided the mechanical energy to generate the electricity? (The density of water is 1000 kg/m³.) Vavg m %3D A gallon of gasoline contains 4.50 × 10' J of energy. How many gallons n of gasoline did the 4148 dams save? n = gal MacRook Pro