Both line emission and line ______________ spectra are characteristic for a specific element
Fill in the blank(s) with correct word
absorption
You might also like to view...
Estimate (a) the heat transfer coefficient for a spherical fuel droplet injected into a diesel engine at 80°C and 90 m/s. The oil droplet is 0.025 mm in diameter, the cylinder pressure is 4800 kPa, and the gas temperature is 944 K. (b) Estimate the time required to heat the droplet to its self-ignition temperature of 600°C.
GIVEN
• An oil droplet injected into a diesel engine
• Initial droplet temperature (To) = 80°C
• Injection velocity (Ud) = 90 m/s
• Droplet diameter (D) = 0.025 mm = 2.5 × 10–5 m
• Cylinder pressure = 4800 kPa
• Gas temperature (T?) = 944 K = 671°C FIND (a) The heat transfer coefficient ( h c) (b) The time (t) required for the drop to reach 300°C ASSUMPTIONS
• Radiative heat transfer is negligible
• The gas has the properties of air and behaves as an ideal gas
• Only the density of the gas is affected by pressure
• Variation of the thermal conductivity of the oil with temperature is negligible
• Fuel has the same properties as unused engine oil
SKETCH
How do astronomers know that the Crab Nebula is the remains of a supernova?
What will be an ideal response?
When a rock is held above the ground, we say it has some potential energy. When we let it go, it falls and we say the potential energy is converted to kinetic energy. Finally, the rock hits the ground. What has happened to the energy?
A) The energy goes into the ground and, as a result, the orbit of the earth about the Sun is slightly changed. B) The energy goes to producing sound and to heating the ground, rock, and surrounding air. C) The rock keeps the energy inside it (saving it for later use). D) It is lost forever. Energy does not have to be conserved. E) It is transformed back into gravitational potential energy.
A bird, accelerating from rest at a constant rate, experiences a displacement of 22 m in 10 s. What is the average velocity?
a. 1.2 m/s b. 2.2 m/s c. 2.4 m/s d. 0 m/s e. 0.5 m/s