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.
Learner's definition of APPRECIATE. 1. [+ object] : to understand the worth or importance of (something or someone) : to admire and value (something or someone). The company strives to make its employees feel appreciated. Living in the city has taught me to appreciate the differences between people.