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3 years ago

The mass of a star can be determined by studying ___.

Physics

2 answers:

oksian1 [2.3K]3 years ago

7 0

Answer:

C. Binary star systems

Explanation:

Citrus2011 [14]3 years ago

4 0

Answer: C. Binary star systems

Let’s see your options:

a) The color of the star: the color is not used in calculating the mass of a star, because it has no relation to it. Think about a red supergiant and a red dwarf: they have the same color, but they are completely different stars, with respectively a big and a small mass.

b) Kepler’s laws: these laws can be applied in what is called the “approximation of 1 body”, which means that is assumed that one body has a much bigger mass than the other and can be considered at rest. This is the case of a star-planet system and the mass that can be calculated is that of the planet.

c) Binary star systems: these are the only cases in which is possible the direct measure of the mass of the stars. Binary systems are classified as follows:
- Visual binaries: each star can be resolved and the motion around the center of mass can be measured.
- Astrometric binaries: only one star is visible, but the presence of the companion can be inferred by the movement of the first star around the system’s center of mass.
- Eclipse binaries: the two stars are not resolved (separated), but the luminosity varies periodically when one star eclipses the other.
- Spectroscopic binaries: the two stars are not resolved, but their spectrum reveals that they are a binary system.
In all these cases we have a “two-body problem” that can be solved by changing system of reference: the motion of bodies 1 and 2 is equivalent to the motion of a body of mass equal to the system’s reduced mass $\mu = \frac{M_{1} \cdot M_{2}}{M_{1} + M_{2}}$ moving in the potential generated by the total mass (M1 + M2) considered at rest. Hence, we can determine the masses of the two stars.

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A 1.2kg ball rolls forward with an acceleration of 1.11 m/s. What is the net force on the ball

grandymaker [24]

Answer:

1.332 N

Explanation:

Net Force = Mass x Acceleration
1.2 x 1.11 = 1.332 N

I'm so sorry if I'm wrong.

8 0

1 year ago

Find the dimension of volume

BlackZzzverrR [31]

Answer:

L^3

Explanation:

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2 years ago

A tennis ball connected to a string is spun around in a vertical, circular path at a uniform speed. The ball has a mass m = 0.15

Oksanka [162]

1) 5.5 N

When the ball is at the bottom of the circle, the equation of the forces is the following:

$T-mg = m\frac{v^2}{R}$

where

T is the tension in the string, which points upward

mg is the weight of the string, which points downward, with

m = 0.158 kg being the mass of the ball

g = 9.8 m/s^2 being the acceleration due to gravity

$m \frac{v^2}{R}$ is the centripetal force, which points upward, with

v = 5.22 m/s being the speed of the ball

R = 1.1 m being the radius of the circular trajectory

Substituting numbers and re-arranging the formula, we find T:

$T=mg+m\frac{v^2}{R}=(0.158 kg)(9.8 m/s^2)+(0.158 kg)\frac{(5.22 m/s)^2}{1.1 m}=5.5 N$

2) 3.9 N

When the ball is at the side of the circle, the only force acting along the centripetal direction is the tension in the string, therefore the equation of the forces becomes:

$T=m\frac{v^2}{R}$

And by substituting the numerical values, we find

$T=(0.158 kg)\frac{(5.22 m/s)^2}{1.1 m}=3.9 N$

3) 2.3 N

When the ball is at the top of the circle, both the tension and the weight of the ball point downward, in the same direction of the centripetal force. Therefore, the equation of the force is

$T+mg=m\frac{v^2}{R}$

And substituting the numerical values and re-arranging it, we find

$T=m\frac{v^2}{R}-mg=(0.158 kg)\frac{5.22 m/s)^2}{1.1 m}-(0.158 kg)(9.8 m/s^2)=2.3 N$

4) 3.3 m/s

The minimum velocity for the ball to keep the circular motion occurs when the centripetal force is equal to the weight of the ball, and the tension in the string is zero; therefore:

$T=0\\mg = m\frac{v^2}{R}$

and re-arranging the equation, we find

$v=\sqrt{gR}=\sqrt{(9.8 m/s^2)(1.1 m)}=3.3 m/s$

7 0

2 years ago

A dart with mass md is launched toward a block of mass mb that is suspended from a string of length L. The dart is moving horizo

Yuki888 [10]

Answer:

A) Impulse is the same for both the objects

B) The higher is the speed, the greater will be the height.

Explanation:

Part a)

The time of interaction of the two bodies i.e the hanging mass and the stick is same. Thus, force caused by dart on the block = force caused by block on the dart. Hence, impulse is the same for both the objects.

Part B

The energy will be conserved in the entire reaction process

Hence, Kinetic energy = potential energy

0.5Mv^2 = gh(md+mb)

H is directly proportional to the square of speed.

Hence, the higher is the speed, the greater will be the height.

5 0

2 years ago

) a wrench 0.6 meters long lies along the positive y-axis, and grips a bolt at the origin. a force is applied in the direction o

Lera25 [3.4K]

Applied Force Direction vector = [0,1,3] force F = j + 4k torque is t = 100 Newton-meters = r x F Wrench is 0.5 meters long on positive side of the y-axis, r = 0.6 = [0,0.6,0] We know torque |t| = |r x F| = |r| x |F| sin theta r x F = |r| x |F| cos theta r x (j + 3k) = |r| x |j + 3k| cos theta => [0,0.6,0] [0,1,3] = 0.6 x squareroot of ((0)^2 + (1)^2 + (3)^2) cos theta => 0.6 = 0.6 x squareroot of (1 + 9) cos theta => cos theta = 1 / squareroot of (10) Calculationg the sin theta, sin theta = squareroot of (1 - (1 / squareroot of (10))^2) = squareroot of (9/10) sin theta = 3 / squareroot of (10) Substituting the values, |T| = |r| x |F| sin theta => 100 = |0.6| x |F| x 3 / squareroot of (10) |F| = (100 x squareroot of (10)) / 1.8 |F| = (1000 / 18) x squareroot of (10) Magnitude of force |F| = 55.55 x squareroot of (10)

6 0

3 years ago