HELP ME please !! statics

Determine the normal reaction on roller A, and the horizontal and vertical components in pin B, to achieve the balance of the element

1. most waves are caused by vibrations. what motion in a transmitting antenna causes the vibrations that produce radio waves? 2. name two common household appliances that produce electromagnetic waves other than radio waves. what kind of electromagnetic waves do they produce? 3. when you are in a car and it passes through a tunnel, the radio signal is sometimes lost. why do you think this happens?

In a closed system, the total energy prior to an energy transformation is the total energy after. a. equal to b. unrelated to c. greater than d. less than

What is the measurement of how fast an object moves relative to a reference point?