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3 years ago

What is the mystery Greene discussion and why does he say it is something we should all care about

Physics

1 answer:

Step2247 [10]3 years ago

6 0

Answer:

The mystery that Greene discusses is that dark energy is causing the expansion of the universe to accelerate. However, this cannot be explained by the laws of Physics.

Explanation:

I majored in Physics

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Vocabulary word for the total amount of charge in a closed system remains constant

Usimov [2.4K]

Answer:

i think this is it i dont know tho A conservation law stating that the total electric charge of a closed system remains constant over time, regardless of other possible changes within the system. "Conservation of charge." YourDictionary. LoveToKnow

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3 years ago

What is the speed of sound for noise that travels 2 km in 5.8

earnstyle [38]

Answer:

2.9

Explanation:

average speed=distance/time taken

=2/5.8

=2.9

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3 years ago

I NEED HELP I AM SO CONFUSED, WILL GIVE BRAIN.

MakcuM [25]

Answer:

210

Explanation:

A ball rolls horizontally off the cliff at a speed of 30 m/s. It takes 7 seconds for the ball to hit the ground. What is the height of the cliff and the horizontal distance traveled by the ball?

S = (1/2)*9.8 m/s^2 * 7^2 = 240.1 m if the ball is very dense so air resistance, and therefore terminal velocity, can be ignored.

S = v * t = 30 m/s * 7 s = 210 m for the horizontal distance, again assuming negligible air resistance.

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3 years ago

A billiard ball is moving in the x-direction at 30.0 cm/s and strikes another billiard ball moving in the y-direction at 40.0 cm

PSYCHO15rus [73]

Explanation:

Given that,

Initial speed of the billiard ball 1, u = 30i cm/s

Initial speed of another billiard ball 2, u' = 40j cm/s

After the collision,

Final speed of first ball, v = 50 cm/s

Final speed of second ball, v' = 0 (as it stops)

Let us consider that both balls have same mass i.e. m

Initial kinetic energy of the system is :

$K_i=\dfrac{1}{2}mu^2+\dfrac{1}{2}mu'^2\\\\K_i=\dfrac{1}{2}m(u^2+u'^2)\\\\K_i=\dfrac{1}{2}m((30)^2+(40)^2)\\\\K_i=1250m\ J$

Final kinetic energy of the system is :

$K_f=\dfrac{1}{2}mv^2+\dfrac{1}{2}mv'^2\\\\K_f=\dfrac{1}{2}m(v^2+v'^2)\\\\K_f=\dfrac{1}{2}m((50)^2+(0)^2)\\\\K_f=1250m\ J$

The change in kinetic energy of the system is equal to the difference of final and initial kinetic energy as :

$\Delta K=K_f-K_i\\\\\Delta K=1250m-1250m\\\\\Delta K=0$

So, the change in kinetic energy of the system as a result of the collision is equal to 0.

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4 years ago

Two resistors, of R1 = 3.93 Ω and R2 = 5.59 Ω, are connected in series to a battery with an EMF of 24.0 V and negligible interna

son4ous [18]

Answer:

2.521 (A); 14.0924 (V)

Explanation:

more info in the attachment, the answers are marked with red colour.

4 0

3 years ago

What is the mystery Greene discussion and why does he say it is something we should all care about ​

What is the mystery Greene discussion and why does he say it is something we should all care about