Answer:
The photoelectric effect
Explanation: hope it helps
The answer would be uranium and thorium. When an alpha ejects a particle, it will create a new atom. So, when uranium ejects an alpha particle, it will produce thorium. They call this process as the alpha decay. Alpha decay often happens on atoms that are abundant nuclei such as uranium, radium, and thorium.
According to Newton's first law of motion, it takes an unbalanced force to move an object at rest.
I hope this helps :)
