4. A train passes a stationary observer. Which of the following best describes how the amplitude and the apparent frequency of the sound waves heard by the observer change as the train
moves away?
A. Both the amplitude and the apparent frequency increase.
B. Both the amplitude and apparent frequency decrease.
C. The amplitude of the sound waves increases, and the apparent frequency decreases.
D. The amplitude of the sound waves decreases, and the apparent frequency increases.

During spring semester at mit, residents of the parallel buildings of the east campus dorms battle one another with large catapults that are made with surgical hose mounted on a window frame. a balloon filled with dyed water is placed in a pouch attached to the hose, which is then stretched through the width of the room. assume that the stretching of the hose obeys hooke's law with a spring constant of 89.0 n/m. if the hose is stretched by 5.80 m and then released, how much work does the force from the hose do on the balloon in the pouch by the time the hose reaches its relaxed length? unitst 3 number-1497 the tolerance is +/-5% open show work click if you would like to show work for this question:

If gases like carbon dioxide and methane make up less than 1% of the total atmosphere, why is it important for scientists to monitor changes in percentages of these gases?

Need asap ‼️ 20 pts which gravitational force field diagram is drawn correctly? (answers in pictures below)