Kenneth observes that as an ambulance approaches him, the pitch of the sound of the siren is higher, and the pitch decreases when the ambulance moves away from him. Which of the following is the possible scientific reason for the situation?
A The wavelength of the sound wave gets shorter, and hence the pitch gets higher
B. The wavelength of the sound wave gets longer, and hence the pitch gets higher
C. The wavelength of the sound wave does not affect the pitch
D. The wavelength of the sound wave changes the speed of the wave

The energy released by a chemical reaction can be measured using a calorimeter. when barium hydroxide octahydrate crystals are reacted with dry ammonium chloride inside of a coffee cup calorimeter, the temperature of the 18.00 g of water in the calorimeter decreases from 30.0°c to 8.0°c. the equation for calculating energy absorbed or released by a reaction is: where q is the energy released or absorbed, m is the mass of water in the calorimeter, cp is the specific heat of water, and δt is the observed temperature change. if the specific heat of liquid water is 4.19 j/g·°c, how much energy was absorbed by the reaction?

Ihave a density of 1.61g/cm^3 and a mass of 28g. find the missing value

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)