The following students measure the density of a piece of lead three times. the density of lead is actually 8.9 g/cm3. considering all of the results, which person’s results are both accurate and precise?
a. jenny: 8.55 g/cm3, 8.34 g/cm3, 8.04 g/cm3
c. lila: 8.89 g/cm3, 8.91 g/cm3, 8.92 g/cm3
b. brad: 8.63 g/cm3, 8.64 g/cm3, 8.65 g/cm3
d. none of the above have precise and accurate measurements.

When a spring is compressed, the energy changes from kinetic to potential. which best describes what is causing this change? work power gravitational energy chemical energy

The slope of a velocity time graph over any interval of time gives the during that interval

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)