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3 years ago

How much heat energy (in megajoules) is needed to convert 7 kilograms of ice at –9°C to water at 0°C?

1 answer:

8 0

The heat required to change the phase of a substance can be calculated by using the formula,

q = mCΔT where q is the heat needed, m is the mass of the substance, C is the specific heat capacity and ΔT is the change in temperature.

q = 7000 g (4.18 J/ g °C) (0°C - (-9°C))
q = 263340 J or .26334 MJ
Hope it's correct! ( If so rank as brainliest answer) :)

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Which statement best explains why elements are matter?

Lisa [10]

Choice D, as if it takes up mass then it is matter

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3 years ago

A student mixes two clear liquids together. After a few minutes, a white powdery solid can be seen settling on the bottom of the

SIZIF [17.4K]

I think the answer is A, please lmk if that is incorrect!

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2 years ago

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A boat traveling at a velocity of 20 m/s leaves island heading east . The boat slows to rest at a rate of 1.5 m/s2 How far away

ioda

The boat's initial velocity is:

$v_0 = 20 m/s$

While the boat's acceleration is

$a=-1.5 m/s^2$

with a negative sign, since the boat is slowing down, so it is a deceleration. The distance traveled by the boat until it comes to a stop can be found by using the following equation:

$v_f^2 -v_0^2 = 2aS$

where vf=0 is the final velocity of the boat and S is the distance covered. Re-arranging the formula, we can find S:

$S=\frac{-v_0^2}{2a}=\frac{-(20 m/s)^2}{2(-1.5 m/s^2)}=133.3 m$

7 0

2 years ago

1) What proportion of U.S. energy today comes from renewable sources? What is the most prevalent form of renewable energy used i

Rudik [331]

Answer:

Eighteen percent

Explanation:

Eighteen percent of all electricity in the US is sourced from renewable energy ,which includes solar , wind, and hydroelectric dam.

Hydroelectric power is currently the largest producer of renewable electricity in the US, generating around 6.5% of the nation's total electricity as well as 45.71% of the total renewable electricity generation.The United States is the fourth largest producer of hydroelectricity in the world after China, Canada and Brazil.

8 0

2 years ago

If the 3rd harmonic has a frequency of 600Hz, the frequency of the fundamental is ____________?

castortr0y [4]

Answer:

Fundamental frequency is 200 Hz.

Explanation:

It is given that,

Frequency of the 3rd harmonic is 600 Hz.

Let f is the fundamental frequency. We need to find the value of f. The frequency of third harmonic is given by :

$3f=600\ Hz$

So, fundamental frequency f is equal to :

f = 200 Hz

So, the fundamental frequency of the harmonics is 200 Hz. Hence, this is the required solution.

4 0

3 years ago