Well for it to be valid you are going to need a hypothesis,control,and variables. The control should be the plant food since it stays constant. And the variables should be the 2 different plants.
The shortened form of the unit that Kevin's bag was weighed in would be Lbs.
Answer:
Observers ahead of the wave observe an apparent increase in wave frequency
Explanation:
This is the Doppler Effect. The frequency of a wave increases when the source approaches the observer and decreases as the source recedes.
B, C, and D are wrong. Observers behind the source notice a decrease in frequency.