Answer:
B
Explanation:
for the motion every night, it is because the Earth spins on its axis.
for the changes over a year, this is because the Earth rotates around the sun.
for the changes over hundreds, thousands or millions of years, this is because the whole solar system (including the Earth, of course) rotates with all the other stars in our galaxy around the center of the galaxy. and each star system has its own orbit (similar to the planets in our solar system).
it is very rare to see objects outside of our galaxy without a telescope, but they change too over a long period of time, because our galaxy not only rotates by also moves through the universe, and these other objects move on their own too.
The answer is A. Only an object in motion has kinetic energy.
As we know that gravitational potential energy is given by
here we have
m = mass = 120 kg
h = height = 8.2 m
now from above formula
so above is the gravitational potential energy of the couch
Answer:
It has very high density, so a small bulb of a thermometer can contain much mercury. Mercury remains liquid state over a quite wide range of temperature because it freezes at 39°C and boils at 357°C.
Explanation:
Answer:
The second trumpeter will be playing at frequency = 515 Hz
Explanation: Given that the note sounds lower and they can hear 20 beats in 4.0 s.
Beat frequency = 20/4 = 5 Hz
Beat frequency = F2 - F1
5 = 520 - F1
F1 = 520 - 5
F1 = 515 Hz
Since the note sound lower, the second trumpeter will be playing at 515 Hz frequency
