When the average kinetic energy of the molecules goes up (a rise in temperature), the average speed of the molecules increases. And lower average kinetic energy of the molecules means they have lower speed. However, a change in average kinetic energy is not directly proportional to a change in average speed. 1.
An appreciation means an increase in the value of a currency. It means a currency is worth more in terms of foreign currency.
That's inflation. Inflation is when a certain form of currency starts to have less value over time. Mainly two things cause it: people's perception of value, and the economic principle of supply and demand. We have already examined some of the ways that people's perceptions of a currency's value can affect its value.