Snell's law states that sin(i) and sin(r) should be proportional, what two conditions are necessary to establish proportionality?

Asap 1. which surface feature of the moon is characterized by mountainous areas? question options: maria terrae regolith craters 2.which statement describes surface features called maria on the moon? question options: layers of dust and rock deep areas of cooled lava deep, rocky and barren valleys highlands and mountainous areas

You are a sales representative for a company that makes a new alternate fuel for vehicles. you have prepared a presentation for the environmental engineers to sell your new product. what question do you expect the audience to ask regarding whether the new fuel will cause less damage to the environment? a. do we have to change any parts of the vehicle to use this alternate fuel? b. will the vehicles get better fuel mileage with the alternate fuel? c. how much greenhouse gas does your fuel produce compared with current fuel sources? d. is the alternate fuel more expensive than fossil fuel?

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.