Answer:
Four; Two; One; Three
Explanation:
During a lab, a student tapes a ruler to a lab table and sets the ruler in motion. A laser detector pointed at the ruler records how many times the ruler vibrates back and forth in a period of time.
Pitch or frequency is defined as the number of cycles per unit time. We can calculate the pitch for each trials i.e.
Trial one, 
Trial two, 
Trial three, 
Trial four, 
Hence, the order of the trials from least to greatest pitch is :
Trial four, Trial two, Trial one and Trial three i.e. option (d) is correct.
Answer:
A vector is a quantity that has both magnitude and direction .
I don't think it has a unity
Answer:
Explanation:
Well, lets say you park your car on the top of a hill, gravitational energy prevents it from the car falling back. Or a snow pack, aka before a potential avalanche. Though gravity cannot keep it safe forever, gravitational energy keeps it from crashing asap. In this case, it gives you time to escape. Altogether, gravitational force keeps the earth in it's atmosphere.
Steam powered boats run from an engine, using power, gears, and cranks to function.
Sailboats use no engine and rely on winds to move and change the direction of the boat.
