I think so it ans wold be d.because if the source approaches the observer more and more wavefront will pass and it get squeezed.so wavelength decreases and frequency increases.
The period T of a pendulum is given by:

where L is the length of the pendulum while

is the gravitational acceleration.
In the pendulum of the problem, one complete vibration takes exactly 0.200 s, this means its period is

. Using this data, we can solve the previous formula to find L:
Answer:
196
Explanation:
subtract 24 from 220 to get your answer.
Answer:
battery
Explanation:
A battery contains stored chemical energy and converts it to electrical energy. (cK.12)