Particles may be emitted in radiactive decay is not ionising?

This question is worth 54 points ! rock falls from a ledge to the ground what energy conversion occurs during this process a potential to kinetic b kinetic to potential c thermal to mechanical d chemical to mechanical

Aparticle travels in a circular orbit of radius 21 m. its speed is changing at a rate of 23.1 m/s2 at an instant when its speed is 37.2 m/s. what is the magnitude of the acceleration (in m/s? ) of the particle?

What practical value did astronomy offer to ancient civilizations?