Question

An inventor wants you to invest money with his company, offering you 10% of all future profits. He reminds you that the brakes on cars get extremely hot when they stop and that there is a large quantity of thermal energy in the brakes. He has invented a device, he tells you, that converts that thermal energy into the forward motion of the car. This device will take over from the engine after a stop and accelerate the car back up to its original speed, thereby saving a tremendous amount of gasoline. Now, you're a smart person, so he admits up front that this device is not 100% efficient, that there is some unavoidable heat loss to the air and to friction within the device, but the upcoming research for which he needs your investment will make those losses extremely small. You do also have to start the car with cold brakes after it has been parked awhile, so you'll still need a gasoline engine for that. Nonetheless, he tells you, his prototype car gets 500 miles to the gallon and he expects to be at well over 1000 miles to the gallon after the next phase of research.

a. Should you invest?

Answer 1

given the thermal energy from the brake to stop

hoowever even if we use all the thermal energy from the brake,

we would only nearly enough power like a back of envelope

concept and calculation is using the specific heat capacity of steel

and the mass of our brake rotor demonstrated.

then can say the amount of energy we would have get is very very limited.

finally can say that invention seems to be a simple for a heat engine.

any heat engine that can operates with only a temperature gradient of 10 degree centigarde

or that is how much our brake rotour get heat is extremely inefficient..

and also can say

electrical and mechanical energy recovery concept,

using a battery or a flywheel or a spring or a some other way to store

mechanical energy in the form of electrical ,

is to be bound most efficient and gearful than this conversion.