Physics Kinematics Level: Misc Level
An object that is thrown vertically upward will return to its original position with the same speed it had initially if air resistance is negligible. If air resistance is appreciable, will this result be altered, and if so, how? (Hint: the accleration due to air resistance is always in the direction opposite to the motion.)
Physics Kinematics Level: Misc Level
When an object moves with constant velocity, does its average velocity during any time interval differ from its instenous velocity at any instant? Please elaborate.
Physics Relativity Level: Misc Level
A certain quasar recedes from Earth at v=0.870c. A jet of material ejected from teh quasar back toward Earth moves at 0.550c relative to the quasar. Find the speed of the ejected material relative to Earth.
Physics Relativity Level: Misc Level
A supertrain of proper length 100 m travels at a speed of 0.95 c as it passes through a tunnel having proper length 50m. As seen by a trackside observer, is the train ever completely within the tunnel? If so, by how much?
Physics Work,Power & Energy Level: Misc Level
A standard automobile b attery is rated at 12 V and 70 ampere hours. Translate those figures into Joules of stored energy. For short periods the battery can deliver a current of 300 A. What is the delivered power in watts?
Physics Rotational Mechanics Level: Misc Level
1. A flywheel has E= 900000 J radius =.5 m voiume=3.3765 m^3 density=7x10^3kg /m^3 Due to its radius and the material (steel) of the flywheel, the maximum angular velocity W max is 3000 revolutions per minute (rpm). Assuming that the flywheel has a 100% efficency, what is the maximum kinetic energy that can be stored in this flywheel)?
Physics Heat & Thermodynamics Level: Misc Level
In a particular biological reaction taking place in the body at 37 degrees C, the change in enthalpy was- 125 kJ/mol and the change in entropy was-126 J/K mol (a) Calculate the change in Gibbs energy. (b) is the reaction spontaneous?(c)Calculate the total change in entropy of the system and surroudings.
Physics Heat & Thermodynamics Level: Misc Level
The enthalpy of vaporization of chloroform CHCI3, is 29.4 kJ/mol at its normal boiling point of 334.88 K (a) calculate the entropy of vaporization of chloroform at this temperature. (b) What is the entropy change in the surroundings?
Physics Heat & Thermodynamics Level: Misc Level
The enthalpy of graphite >>>> diamond phase transition, which under 100 kbar occurs at 2000 K, is +1.9 kJ/mol. Calculate the entropy of transition.
Physics Heat & Thermodynamics Level: Misc Level
What is the change in entropy 100g of water when it is heated from room temperature (20 degreesC) to body temperature (37 degress C) Use Cp, m=75.5 J /K mol
Physics Heat & Thermodynamics Level: Misc Level
Whenever a gas expands -when we exhale, when a flask is opened, and so on -the gas undergoes an increase in entropy. A sample of methane gas of mass 25 g at 250 K and 185 kPa expands isothermally and (a)reversble, (b) ireversible until its pressure is 2.5 kPa. Calculate the change in entropy of the gas.
Physics Heat & Thermodynamics Level: Misc Level
A sample of carbon diooxide that initially occupies 15.0 dm cubed at 250 K and 1.00atm is compressed isothermally. into what volumemust the gas be compressed to reduce entropy by 10.0 J/K?
Physics Heat & Thermodynamics Level: Misc Level
Calculate the change in molar entropy when carbon dioxide expands isothermally from 1.5 dm cubed to 4.5 dm cubed.
Chemistry Mole Concept Level: Misc Level
A sample of aluminum of mass 1.25 kg is cooled at constant pressure from 300K to 26K.Calculate the energy that must be removed as heat and the change in entrpy of the sample. The molar heat capacity of aluminum is 24.35 J/K mol.
Physics Relativity Level: Misc Level
A rectangular billboard in space has the dimensions 10 meters. by 20 meters. How fast and in what direction with respect to the billboard would a space traveler have to pass to for the billboard to appear square?
