The surface area of an adult human is about 1.8 m 2 . Suppose a person with a skin temperature of 34°C is standing with bare skin in a room where the air is 25°C but the walls are 17°C. a. There is a “dead-air” layer next to your skin that acts as insulation. If the dead-air layer is 5.0 mm thick, what is the person's rate of heat loss by conduction ? b. What is the person’s net radiation loss to the walls? The emissivity of skin is 0.97. c. Does conduction or radiation contribute more to the total rate of energy loss? d. If the person is metabolizing food at a rate of 155 W, does the person feel comfortable, chilly, or too warm?
The surface area of an adult human is about 1.8 m 2 . Suppose a person with a skin temperature of 34°C is standing with bare skin in a room where the air is 25°C but the walls are 17°C. a. There is a “dead-air” layer next to your skin that acts as insulation. If the dead-air layer is 5.0 mm thick, what is the person's rate of heat loss by conduction ? b. What is the person’s net radiation loss to the walls? The emissivity of skin is 0.97. c. Does conduction or radiation contribute more to the total rate of energy loss? d. If the person is metabolizing food at a rate of 155 W, does the person feel comfortable, chilly, or too warm?
The surface area of an adult human is about 1.8 m2. Suppose a person with a skin temperature of 34°C is standing with bare skin in a room where the air is 25°C but the walls are 17°C.
a. There is a “dead-air” layer next to your skin that acts as insulation. If the dead-air layer is 5.0 mm thick, what is the person's rate of heat loss by conduction?
b. What is the person’s net radiation loss to the walls? The emissivity of skin is 0.97.
c. Does conduction or radiation contribute more to the total rate of energy loss?
d. If the person is metabolizing food at a rate of 155 W, does the person feel comfortable, chilly, or too warm?
Chemical pathways by which living things function, especially those that provide cellular energy, such as the transformation of energy from food into the energy of ATP. Metabolism also focuses on chemical pathways involving the synthesis of new biomolecules and the elimination of waste.
Two objects (m₁ = 4.75 kg and m₂
2.80 kg) are connected by a light string passing over a light, frictionless pulley as in the figure below. The 4.75-kg object is released from rest at a point h = 4.00 m above the table
mg
m
(a) Determine the speed of each object when the two pass each other.
m/s
(b) Determine the speed of each object at the moment the 4.75-kg object hits the table.
m/s
(c) How much higher does the 2.80-kg object travel after the 4.75-kg object hits the table?
m
A cell of negligible internal resistance is connected to three identical resistors. The
current in the cell is 3.0 A.
The resistors are now arranged in series.
What is the new current in the cell?
A negatively charged sphere is falling through a magnetic field.
north pole
of magnet
direction of motion
south pole
of magnet
What is the direction of the magnetic force acting on the sphere?
Chapter 12 Solutions
College Physics: A Strategic Approach (3rd Edition)
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