What year did alexander graham bell invent the telephone

Acommercial passenger jet can travel up to 970 km/hr at an altitude of 30,000 feet. at this speed, how long will it take the jet to travel 1,865 kilometers? a. 2.3 hrs b. 1.9 hrs c. 1.7 hrs d. 1.5 hrs

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

An insulated 40 ft^3 rigid tank contains air at 50 psia and 120°f. a valve connected to the tank is now opened, and air is allowed to escape until the pressure inside drops to 25 psia. the air temperature during this process is kept constant by an electric resistance heater placed in the tank. determine the electrical work done during this process.