Which of the following is not a key characteristics of thermal equilibrium? two objects must be in contact with each other
they must be at the same temperature
There must be no net thermal energy transfer
They must have different temperature

fghbdt gjdtyg thd tghbtrg htd

step-by-step explanation:

y htf dfh drthf hdt hdthyty hty

it's when something is going so fast it makes a loud noise, breaking the sound barrier, for example: a jet makes a loud noise, not only cause of the jet but because they reached a point where they went so fast that you can year the noise from various parts, kinda like a police car, lets say the car was going   so fast that you hear the siren of the cop car right next to you, but the car is probably a mile a way, it's cos the siren was next to you a few seconds if you understand me