Which is a symptom of the common cold

How is sound energy produced a. vibrating objects b. objects being heated c. temperature differences d. stationary objects

Yvette hangs a 2.4kg bird feeder in the middle of a rope tied between two trees. the feeder creates a tension of 480 n in each side of the the rope.

Scientific models are based on current knowledge, which can limit their effectiveness when new discoveries are made.