Bicycling on a warm day. If the air temperature is the same as the temperature of your skin (about 30°C), your body cannot get rid of
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- A styrofoam container used as a picnic cooler contains a block of ice at 0°C. If 564 g of ice melts in 1 hour, how much heat energy per second is passing through the walls of the container? The heat of fusion of ice is 3.33 x 10° J/kg. Answer in units of W.arrow_forwardOverall, 80% of the energy used by the body must be eliminated as excess thermal energy and needs to be dissipated. The mechanisms of elimination are radiation, evaporation of sweat (2,430 kJ/kg), evaporation from the lungs (38 kJ/h), conduction, and convection. A person working out in a gym has a metabolic rate of 2,500 kJ/h. His body temperature is 37°C, and the outside temperature 22°C. Assume the skin has an area of 2.0 m2 and emissivity of 0.97. (o = 5.6696 × 10-8 w/m2 · K4) (a) At what rate is his excess thermal energy dissipated by radiation? (Enter your answer to at least one decimal place.) 1.8e2 W (b) If he eliminates 0.44 kg of perspiration during that hour, at what rate is thermal energy dissipated by evaporation of sweat? (Enter your answer to at least one decimal place.) 3.0e2 W (c) At what rate is energy eliminated by evaporation from the lungs? (Enter your answer to at least one decimal place.) 10.6 W (d) At what rate must the remaining excess energy be eliminated…arrow_forwardOne strategy when on a diet is to drink ice water. The body must burn calories to warm the water from 0°C to a body temperature of 37°C. Assume a dieter drinks 2.3 kg (i.e., 2.3 L) of ice water every day. The specific heat of water is 4.186 × 103 J/(kg⋅°C). Part (a) How much energy, in joules, does the dieter’s body need to provide in order to warm the water over a full year. Take 365 days in a year. Part (b) One pound of fat supplies 3500 kcal (Cal) to the body, where 1 kcal (Cal) = 4.186 × 103 J. How much fat, in pounds, can the dieter hope to lose in a year by drinking ice water rather than water at body temperature?arrow_forward
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- A 1.0 x 102-kg steel support rod in a building has a length of 2.0 m at a temperature of 20.0°C. The rod supports a hanging load of 6.0 x 103 kg. Find (a) the work done on the rod as the temperature increases to 40.0°C, (b) the energy Q added to the rod (assume the specific heat of steel is the same as that for iron), and (c) the change in internal energy of the rod.arrow_forwardYou want to use an electric stove to heat some water. You place a pot filled with 1500 g of water at room temperature (25 °C) on the stove (the charaterisitics of the pot can be neglected). In order to heat the water faster, you also use an electric beater, which does 120 J of work per second. After 9 minutes the water starts boiling (100 °C). Specific heat capacity of water is 4.2 J/(g*°C). By how much has the energy of the surroundings changed?arrow_forwardA crate of fruit with a mass of 31.0 kg and a specific heat capacity of 3600j/(kgxk) slides 8.40m down a ramp inclined at an angle of 39.4 degrees below horizontal. if the crate was at rest at the top of the incline and has a speed of 2.85 m/s at the bottom, how much work wf was done on the crate by friction? if an amount of heat equal to the magnitude of the work done by friction is absorbed by the crate of fruit and the fruit reaches a uniform final temperature what is its temperature change?arrow_forward
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