Which best describes cosmic microwave background radiation

If an athlete runs once around a track, back to the starting line, her average velocity is zero. true or false?

Suppose a diode consists of a cylindrical cathode with a radius of 6.200×10^−2 cm , mounted coaxially within a cylindrical anode with a radius of 0.5580 cm . the potential difference between the anode and cathode is 260 v . an electron leaves the surface of the cathode with zero initial speed (v initial=0). find its speed vfinal when it strikes the anode.

Acar travels in reverse. it covers 150 meters in 12 seconds what is the velocity of the car what is the speed of the car