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S_A_V [24]
3 years ago
5

We determine the distance of a Cepheid in another galaxy by

Physics
1 answer:
Triss [41]3 years ago
5 0

Answer:

We determine the distance of a Cepheid in another galaxy by <em>b) determining its luminosity from the period-luminosity relation and then applying the inverse square law.</em>

<em>Explanation:</em>

Cepheid stars are stars that periodically brighten up or dim. This kind of behaviour allows them to be used as cosmic yardsticks out to a distance of a few tens of millions of light-years. The continuous luminosity variations in these stars allows their period to be measured accurately.

The astronomer Henrietta Levitt discovered that there is a relationship between a Cepheid's brightness and its' pulsation period. This relation was used to measure distances to nearby galaxies. The brighter the star, the longer the period.

The inverse square law for light describes that the intensity of light is inversely proportional to the squared distance of the source. This means that as the distance increases, the intensity of the light decreases. The mathematical expression is:

I ∝ 1 / d²

where

  • d is the distance

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During a safety crash, a car impacts a solid concrete barrier and and comes to rest in 0.10s. In a second test, an identical car
kirill [66]

Answer:

The correct answer is C

Explanation:

Change is momentum can be described as the change in the product of mass and velocity of a body. Every moving object as a momentum and the higher the momentum of this object, the harder it is to stop. Impulse (a force), which is sometimes used to describe change in momentum can be described as the product as force multiplied by time.

From the description above, it can be deduced that an increase in impulse can lead to a greater change in momentum. And an increase in impulse can be brought about by an increase in the time it takes a body to be brought to rest after collision. And since the car that hit the water barrels was brought to rest at a longer time, it has a greater change in momentum

8 0
3 years ago
Two identical small charged spheres are a certain distance apart, and each one initially experiences an electrostatic force of m
monitta

Answer:

1/4F

Explanation:

We already know thatThe electrostatic force is directly proportional to the product of the charge, from Coulomb's law.

So F α Qq

But if it is now half the initial charges, then

F α (1/2)Q *(1/2)q

F α (1/4)Qq

Thus the resultant charges are each halved is (1/4) and the first initial force experienced at full charge.

Thus the answer will be 1/4F

3 0
3 years ago
You’re still in a redecorating mood and want to move a 35kg bookcase to a different place in the living room. You exert 58 N on
CaHeK987 [17]

Answer: 0.16

Explanation:

Newton's second law states that the resultant of the forces exerted on the bookcase is equal to the product between the mass (m) and the acceleration (a):

F-F_f = ma

where

F = 58 N is the force applied

Ff is the frictional force

Substituting, we find the frictional force

F_f = F-ma=58 N-(35 kg)(0.12 m/s^2)=53.8 N

The frictional force has the form:

F_f = \mu mg

where \mu is the coefficient of kinetic friction. Re-arranging the formula, we can find the coefficient:

\mu=\frac{F_f}{mg}=\frac{53.8 N}{(35 kg)(9.8 m/s^2)}=0.16

4 0
4 years ago
A 2-meter high wave with a wavelength of 100 meters and period of 20 seconds would be moving how fast?
hammer [34]
Velocity of wave= wavelength/wave period;
i.e., 100/20=5 meter/sec
8 0
3 years ago
In the modern atomic model the number of ________ in a neutral atom is the same as the number of protons.
MrRissso [65]

In the modern atomic model the number of electrons in a neutral atom is the same as the number of protons.

An atom contain, three fundamental particles, electron, proton, and neutron, neutron is charge less, there the charge of the atom is determined by the number of proton, and number of electron, Atoms are electrically neutral, it is only possible when number of electrons in an atom is equal to the number of proton.

3 0
3 years ago
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