Eli rolled a ball down the cement sidewalk as hard as he could. the ball rolled for less than a minute before it came to a stop. what force acted to slow and finally stop the ball?

Asample of silver (with work function ? = 4.52 ev) is exposed to an ultraviolet light source (? = 200 nm), which results in the ejection of photoelectrons. what changes will be observed if: silver is replaced with copper (? = 5.10 ev) more photoelectrons ejected no photoelectrons are emitted fewer photoelectrons ejected more energetic photoelectrons (on average) less energetic photoelectrons (on average)

In the following redox reaction which is the oxidizing agent and which is the reducing agent? alcl3 + na nacl + al

All cells are made of four types of acids, lipids, proteins, and carbohydrates.