a) A marathon runner produces about 225 watts of muscle output and 4 times as much heat. How many watts end up as heat?
b) How many cups/hour of water will the heat in 4.a evaporate?
a) A marathon runner produces about 225 watts of muscle output and 4 times as much...
If a heat blanket uses 80.0 watts of power, how much does a 55.0 kg human heat up in 1 hour? Assume the human is mostly water and water has heat capacity 4.18 J/goC
If the air temperature is the same as the temperature of your skin (about 30.0 oC), your body cannot get rid of heat by transferring it to the air. In that case, it gets rid of the heat by evaporating water (sweat). During bicycling, a typical 70.0kg person's body produces energy at a rate of about 53.6 W due to metabolism, 80.0% of which is converted to heat. How many kilograms of water must the person's body evaporate in an...
reases to 1.75 x 105Pa, what is the new temperature of the gas? 4) How much heat in kilocalories is required to evaporate 0.75kg of water that is originally at 250C? Assume that at the end all of the water has evaporated, and the steam is at 100.00C
1. A college student produces about 126 kcal of heat per hour on the average. What is the rate of energy production in joules? __________kJ/h 2. On a brisk walk, a person burns about 330 Cal/h. At this rate, how many hours of brisk walking would it take to lose 1 lb of body fat? (A pound of body fat stores an amount of chemical energy equivalent to 3,500 Cal.) __________ h 3.How much heat is necessary to change 495...
A car engine whose output power is 145 hp operates at about 16 % efficiency. Assume the engine's water temperature of 79 ∘C is its cold-temperature (exhaust) reservoir and 495 ∘C is its thermal "intake" temperature (the temperature of the exploding gas-air mixture). What is the ratio of its efficiency relative to its maximum possible (Carnot) efficiency? Estimate how much power (in watts) goes into moving the car. How much heat, in joules and in kcal, is exhausted to the...
2. Running up the stairs (5 pts). Time how long it takes for you (or a friend) to run as fast as possible up a staircase. Measure the height of one step and count the steps to find how high you climbed. a) How much mechanical energy did you produce to climb the stairs? b) What was the average mechanical power produced during your climb? c) Estimate the muscle mass in your upper legs (quadriceps, hamstrings, and buttocks). (Recall that...
Each pound of fat contains 3500 food calories. When the body
metabolizes food, 80.5% of this energy goes to heat. Suppose you
decide to run without stopping, an activity that produces 1340 W of
metabolic power for a typical person.
Part A) For how many hours must you run to burn up 1 lb of
fat?
Part B) If you followed your planned exercise program, how much
heat would your body produce when you burn up a pound of fat?...
A firm produces output according to the production function: Q = F(K,L) = 2K + 2L. a. How much output is produced when K = 2 and L = 3? b. If the wage rate is $65 per hour and the rental rate on capital is $35 per hour, what is the cost-minimizing input mix for producing 4 units of output? Capital: Labor:
The average human produces about 15 g of sweat per minute during intense activities. a. If a jogger runs for 30 mins and evaporates all of the sweat he produces after his run, how much heat was transferred from his body to the sweat? Assume the jogger is always seating, the sweat’s initial temperature is 37°C, and that sweat has the same specific heat and latent heat as water. b. A heat stroke occurs when a human’s body temperature reaches...
9. A firm produces output according to a production function Q = F(K,L) min [2K,4L]. a. How much output is produced when K-2 and L = 3? b. If the wage rate is $30 per hour and the rental rate on capital is $10 per hour, what is the cost-minimizing input mix for producing 4 units of output? How does your answer to part b change if the wage rate decreases to $10 per hour but the rental rate on...