Which activity can be termed as an economic activity?

Identify the colloquial speech. yo! come over here! i have to tell ya somethin’. a. yo c. somethin’ b. ya d. all of the above

Two identical stars with mass m orbit around their center of mass. each orbit is circular and has radius r, so that the two stars are always on opposite sides of the circle. (a) find the gravitational force of one star on the other. (b) find the orbital speed of each star and the period of the orbit. (c) how much energy would be required to separate the two stars to infinity?

Which best describes the difference between internal and thermal energy?