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marin [14]
3 years ago
6

An object falls with an acceleration of 9.8 m/s2. What is its speed after 2 s?

Chemistry
1 answer:
Iteru [2.4K]3 years ago
5 0
Acceleration is the rate at which velocity changes; here we are told the speed increases by 9.8m/s for each second of travel

assuming the object starts at rest, the object has a speed of 9.8m/s after one second, and a speed of 19.6m/s after two

mathematically, we write

v= at

where v is the velocity, a is the acceleration and t is the time of travel

so v= at = 9.8m/s/s x 2s = 19.6m/s
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Estimate the number of moles of water in all the Earth's oceans. Assume water covers 75% of the Earth to an average depth of 3 k
o-na [289]

Answer:

there are approximately n ≈ 10²² moles

Explanation:

Since the radius of the earth is approximately R=6378 km= 6.378*10⁶ m , then the surface S of the earth would be

S= 4*π*R²

since the water covers 75% of the Earth's surface , the surface covered by water Sw is

Sw=0.75*S

the volume for a surface Sw and a depth D= 3 km = 3000 m ( approximating the volume through a rectangular shape) is

V=Sw*D

the mass of water under a volume V , assuming a density ρ= 1000 kg/m³ is

m=ρ*V

the number of moles n of water ( molecular weight M= 18 g/mole = 1.8*10⁻² kg/mole ) for a mass m is

n = m/M

then

n = m/M = ρ*V/M = ρ*Sw*D/M = 0.75*ρ*S*D/M = 3/4*ρ*4*π*R² *D/M = 3*π*ρ*R² *D/M

n=3*π*ρ*R² *D/M

replacing values

n=3*π*ρ*R² *D/M = 3*π*1000 kg/m³*(6.378*10⁶ m)² *3000 m /(1.8*10⁻² kg/mole) = 3*π*6.378*3/1.8 * 10²⁰ = 100.18 * 10²⁰ ≈ 10²² moles

n ≈ 10²² moles

8 0
3 years ago
Read the given equation:
Assoli18 [71]

Answer:

D.

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Which best describe the isovolumetric contraction phase of the cardiac cycle?
cluponka [151]
The name isovolumetric indicates that there is no change in volume that takes place and this only occurs when all of the valves within the heart are shut.
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m_a_m_a [10]

Answer:

Kinetic energy is the energy that an object has because of its motion. The molecules in a substance have a range of kinetic energies because they don't all move at the same speed. As a substance absorbs heat the particles move faster so the average kinetic energy and therefore the temperature increases.

6 0
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1. The density of a bar of soap is 0.8 g/mL. If the mass of the soap is 108.5 9.
astra-53 [7]

Answer:

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Explanation:

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