Ariver current has a velocity of 5 km/h relative to the shore. a boat moves in the same direction as the current at 4 km/h relative to the river. how do you calculate the velocity of the boat relative to the shore?

subtract the boat’s velocity from the river’s velocity

add the river’s velocity to the boat’s velocity

divide the river’s velocity by the boat’s velocity

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)

Aheavy piece of hanging sculpture is suspended by a90-cm-long, 5.0 g steel wire. when the wind blows hard, the wire hums at its fundamental frequency of 80hz. what is the mass of the sculpture?

According to piaget’s stages of cognitive development, the child does not differentiate between self and other objects. the child repeats rewarding activities, discovers new ways to get what he or she wants, and may have imaginary friends. which period is described?