Answer:
Part a)

Part b)

Explanation:
Part a)
If block is sliding up then net force must be zero and friction will be in opposite to the direction of motion of the block


so we have





Part b)
If block is sliding down then net force must be zero and friction will be in opposite to the direction of motion of the block


so we have





Um this doesn't make since to me since you did not clearly state your awnser
Justin notices a particular type of caterpillar feeds only on cottonwood trees in his neighborhood.In which way has Justin increased his scientific knowledge, Justin increased his powers of scientific observation. His observation is empirical evidence. Empirical relies on observation and experimentation.
It will help you..........