A spider falling from the ceiling quickly comes to a terminal velocity because * a. the resultant downward force is reduced to zero since the viscous drag force increases until it is equal to the weight of the spider
b. the weight of the air displaced by the spider is equal to its own weight
c. the buoyancy force plus the viscous drag force is equal in magnitude to the weight of the spider
d. the weight of the spider is equal in magnitude to the buoyancy force on it

Acar moves at 12m/s and coasts up a hill with a uniform acceleration of -1.6m/s2. how far has it traveled after 6.0s?

Air enters a gas turbine with two stages of compression and two stages of expansion at 100 kpa and 17°c. this system uses a regenerator as well as reheating and intercooling – the intercooler returns the air to the inlet temperature. the pressure ratio across each compressor is 4 ; 300 kj/kg of heat are added to the air in each combustion chamber; and the regenerator operates perfectly while increasing the temperature of the cold air by 20°c. determine the system’s thermal efficiency. assume isentropic operations for all compressor and the turbine stages and use constant specific heats at room temperature. (0.378)

While carrying a heavy box up the stairs,you set the box on a step and rest. then you pick up the box and carry it to the top of the stairs. describe these actions in terms of balanced and unbalanced forces acting on the box.