What is linear expansitivity

Phase changes are chemical changes. true or false

What is the average speed of a car that travels 40 mph for 1 hour and 60 mph in another hour?

An ideal otto cycle has a compression ratio of 10.5, takes in air at 90 kpa and 40°c, and is repeated 2500 times per minute. using constant specific heats at room temperature, determine the thermal efficiency of this cycle and the rate of heat input if the cycle is to produce 90 kw of power.