1. 168.1 Hz
To find the apparent frequency heard by the driver in the car, we can use the formula for the Doppler effect:
where
f is the original sound of the horn
v is the speed of sound
is the velocity of the observer (the driver and the car), which is positive if the observer is moving towards the source and negative if it is moving away
is the velocity of the sound source (the train), which is positive if the source is moving away from the observer and negative otherwise
In this problem we have, according to the sign convention used:
Substituting, we find:
2. 
The speed of light can be calculated as
where
d is the distance travelled
t is the time taken
In this problem:
is the total distance travelled by the laser beam (twice the distance between the Earth and the Moon)
t = 2.60 s is the time taken
Substituting in the formula,
Answer:
The correct answer would be A.
Explanation:
I have gotten this answer many times and have never failed once just trust me.
Answer:
D. By comparing traits
Explanation:
Because age isn't genetic, as well as names, as well as who discovered, but traits are genetic.
To be effective, an exercise program must have an aerobic
form, portion for strength enhancement, and a stretching part. These three
things are essential because they each target specific improvements in your
body. For example, aerobics can help you maintain your body’s fitness or make
it better. This usually targets your heart rate and ensures that you burn fat
while doing so. Second is strength enhancement; this will make sure that your
body becomes better – not just in a feeble state. Lastly is stretching, your
muscles are like rubber bands. You cannot end or start your exercise program
without stretching simply because they can damage your muscles as well. Aside
from this, stretching can stop you from shocking your body into a physical
activity, which may cause you to lose consciousness or have undue stress and fatigue.
Answer:
The minimum frequency is 702.22 Hz
Explanation:
The two speakers are adjusted as attached in the figure. From the given data we know that
=3m
=4m
By Pythagoras theorem
Now
The intensity at O when both speakers are on is given by
Here
- I is the intensity at O when both speakers are on which is given as 6
- I1 is the intensity of one speaker on which is 6
- δ is the Path difference which is given as
- λ is wavelength which is given as
Here
v is the speed of sound which is 320 m/s.
f is the frequency of the sound which is to be calculated.
where k=0,1,2
for minimum frequency 
, k=1
So the minimum frequency is 702.22 Hz
