PLEASE HELP The position of a particle moving on the x- axis is x= 7.8 + 9.2t -2.1t³ where x is in meters and t is in seconds. What's it's velocity at t= 3.5 seconds and is the velocity constant or continuously changing?​

In a heat engine if 1000 j of heat enters the system the piston does 500 j of work, what is the final internal energy of the system if the initial energy was 2000 j? 1. write the equation 2.list out your known variables 3.plug the numbers into the equations 4.solve 5.write your solution statement that includes initial energy and final

An ionic compound can conduct electricity when a it is dissolved in water b its crystals are ground into powder c it is in solid form d it is heated to just below its melting point

Awave that is traveling fast can be said to have a high a. frequency b. speed c. wavelength d. amplitude e. period f. none of these