A stone floor feels cold to the bare feet but a carpet on the same floor feels warm. This is because
A) the floor and carpet are at different temperatures
B) the stone conveys the heat away from the feet more rapidly than the carpet
C) the carpet is a better conductor of heat than the stone
D) the human body maintains a constant temperature
A) the floor and carpet are at different temperatures
B) the stone conveys the heat away from the feet more rapidly than the carpet
C) the carpet is a better conductor of heat than the stone
D) the human body maintains a constant temperature
Answer & ExplanationAnswer: B) the stone conveys the heat away from the feet more rapidly than the carpet
Explanation:
Both the floor and the carpet have the same temperature as both are exposed to the same atmosphere. But the former conducts away the heat from the feet better than the carpet as the latter is a non-conductor. So the feet losing more heat, the floor appears cooler to the feet.
The green house effect. The waves of smaller wavelength from the sun enter inside the car through the glass windows and are absorbed. The waves of larger wavelength emitted from inside cannot get out through the glass, but remain inside and make it terribly hot.
Which of the following definitions describes a physical hazard?
A) The most commonly thought of hazard in construction. This hazard includes radiation, extreme temperatures, noise, and vibration.
B) These hazards can lead to injuries to the joints or muscles by way of heavy, frequent lifting, repetitive tasks.
C) Can be present in dust, fumes, liquids, solids, mists, vapors, or gases of products used at a site or released during a construction job
D) Microorganisms, such as bacteria, fungus, mold, or viruses that can cause illness.
A) The most commonly thought of hazard in construction. This hazard includes radiation, extreme temperatures, noise, and vibration.
B) These hazards can lead to injuries to the joints or muscles by way of heavy, frequent lifting, repetitive tasks.
C) Can be present in dust, fumes, liquids, solids, mists, vapors, or gases of products used at a site or released during a construction job
D) Microorganisms, such as bacteria, fungus, mold, or viruses that can cause illness.
Answer & ExplanationAnswer: A) The most commonly thought of hazard in construction. This hazard includes radiation, extreme temperatures, noise, and vibration.
Explanation:
A physical hazard is defined as "A factor within the environment that can harm the body without necessarily touching it."
Vibration and noise are examples of physical hazards.
Physical hazards include but aren't limited to electricity, radiation, pressure, noise, heights and vibration amongst many others.
A) coagulation of particles and the dispersed phase
B) erratic flashes of light
C) molecules of the dispersion medium colliding with dispersed phase particles
D) All the above
A) coagulation of particles and the dispersed phase
B) erratic flashes of light
C) molecules of the dispersion medium colliding with dispersed phase particles
D) All the above
Answer & ExplanationAnswer: C) molecules of the dispersion medium colliding with dispersed phase particles
Explanation:
When their is a colloid in the solution, then it will show the Brownian movement, such as dust particle in the air will show the Brownian movement.
Hence, Brownian movement arises due to the impact of the molecules of the dispersion medium with the colloidal particles. It has been postulated that the impact of the molecules of dispersion medium on the colloidal particles are unequal.
This leads to the zig-zag (random) motion of the colloidal particles.
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