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snow_lady [41]
2 years ago
15

Why do comets only have tails when they are near the sun?.

Physics
1 answer:
kaheart [24]2 years ago
4 0
When far from the sun, a comet is like a stone rolling around the universe. But when it approaches the sun, the heat evaporates the comet's gases, causing it to emit dust and micro particles, electrons and ions.
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A 55-kg mountain climber, starting from rest, climbs a vertical distance of 701 m. At the top, she is again at rest. In the proc
aksik [14]

Answer:

7.75%

Explanation:

mass of climber, m = 55 kg

height, h = 701 m

Qc = 4.5 x 10^6 J (heat exhaused by the body)

Work = m x g x h

W = 55 x 9.8 x 701

W = 377839 J

W = QH - Qc

Where, QH is the heat input

QH = 377839 + 4.5 x 10^6

QH = 4877839 J

So, the efficiency

e = W / QH

e = 377839 / 4877839

e = 0.0774 = 7.75 %

Thus, the efficiency of the body is 7.75 %.

3 0
3 years ago
The temperature at which the velocity of sound in air is twice its velocity at 15°C
Elena L [17]

With the use of below formula, at 879 °C,  velocity will be double the velocity at 15 °C.

<h3>What is the relationship between Velocity and sound ?</h3>

The velocity of sound waves in air is proportional to the square root of Thermodynamic temperature. That is, V = K\sqrt{T}

Given that the temperature at which the velocity of sound in air is twice its velocity at 15°C, Let us make use of the formula;

(v2/v1) = √(T2 / T1)

Where

  • v2 = final velocity
  • v1 = initial velocity
  • T2 = final absolute temperature
  • T1 = initial temperature.

Recall that absolute temperature = °C + 273.

If v2 = 2 × v1 and temperature in degree Celsius = 15°C, then,

Temperature in Kelvin K = 15 + 273 = 288

Substitute all the parameters into the formula

(2 × v1)/v1 = √(T2/288)

2 = √ (T2 /288)

Square both sides

4 = (T2/288)

T2 = 4 × 288

T2 = 1152K

Temperature in degrees Celsius = 1152 - 273 = 879 °C.

Therefore, at 879 °C,  velocity will be double the velocity at 15 °C.

Learn more about sound waves here: brainly.com/question/13105733

#SPJ1

8 0
2 years ago
A 7 kg ball of clay traveling at 12 m/s collides with a 25 kg ball of clay traveling in the
ANEK [815]

Answer:

<em><u>Given: </u></em>

m1 = 7 kg

V1 = 12 m/s

m2 = 25 kg

V2 = 6 m/s

<em><u>To find:</u></em>

Combined speed of two balls stick together after collision V = ?

<em><u>Solution:</u></em>

<em>According to law of conservation of momentum,</em>

m1V1 + m2V2 = (m1+m2)V

7×12 + 25×6 = (7+25)V

84 + 150 = 32V

V = 234/32

V = 7.31 m/s

Combined speed of two ball is 7.31 m/s

<em><u>Thanks for joining brainly community!</u></em>

4 0
2 years ago
Mixing salt in water is an example of physical change
galina1969 [7]

EXPLAIN MORE!!! i need more detail if i can help you

6 0
3 years ago
If a dolphin swims at 15 m/s for 30 seconds, how far would the dolphin swim?
Olegator [25]
It would swim 30*15 metres, which is 450 metres.
7 0
3 years ago
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