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3 years ago

A 65 kg diver jumps off a 10 m platform.

Chemistry

1 answer:

kramer3 years ago

8 0

Answer:

1. 6.37 KJ

2. 3.185 KJ

Explanation:

Gravitational potential energy is a form of potential energy with respect to the force of gravity.

Gravitational potential energy = mass x acceleration due to gravity x height

i.e PE = m x g x h

1. At the top of the platform; mass = 65 kg, acceleration due to gravity = 10 m/ $s^{2}$ , and height = 10 m.

Gravitational potential energy = 65 x 9.8 x 10

= 6370 Joules

The gravitational potential of the diver at the top of the platform is 6.37 KJ.

2. Halfway down; mass = 65 kg, acceleration due to gravity = 10 m/ $s^{2}$ , and height = 5 m.

Gravitational potential energy = 65 x 9.8 x 5

= 3185 Joules

The gravitational potential energy of the diver halfway down is 3.185 KJ.

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What is the initial temperature (°C) of a system that has the pressure decreased by 10 times while the volume increased by 5 tim

Ede4ka [16]

Answer:

300K

Explanation:

Given pressure of the system decreased by 10 times which means $P_{2} =\frac{P_{1} }{10}$

Given the volume of the system increased by 5 times which means $V_{2} =5\times V_{1}$

Given final temperature $T_{2}=150K$

Let the initial temperature be $T_{1}$

We know that PV=nRT

As n and R are constant $\frac{PV}{T}=constant$

$\frac{P_{1}V_{1} }{T_{1}} =\frac{P_{2}V_{2}}{T_{2}}$

$T_{1} =\frac{P_1V_1}{P_2V_2} T_{2}$

$T_{1} =2\times T_{2}$

T1=300K

8 0

3 years ago

Round 23.455 cm into 4 significant figures: cm

lina2011 [118]

23.450
i did this in chem so this should be right

7 0

3 years ago

Many computer chips are manufactured from silicon, which occurs in nature as SiO2 . When SiO2 is heated to melting, it reacts wi

Ierofanga [76]

Answer:

a. Theoretical yield of Si = 72.58 kg

b. Percent Yield = 91.2 %

Explanation:

The chemical reaction involved is: SiO₂ (l) + 2C (s) → Si (l) + 2CO (g)

The stoichiometric ratio = 1 mol SiO₂ ÷ 2 mol C = 0.5 mol SiO₂ ÷ 1 mol C

Given: mass of SiO₂: w₁ = 155.3kg = 155.3 × 10³g, mass of C: w₂ = 79.3kg = 79.3 × 10³g, mass of Si: w₃ = 66.2kg = 66.2 × 10³g (∵ 1 kg =1000g)

Molar mass of SiO₂: m₁ = 60.08 g/mol, atomic mass of C: m₂ = 12.01 g/mol, atomic mass of Si: m₃ = 28.08 g/mol

Number of moles of SiO₂ taken: n₁ = w₁ ÷ m₁ = 155300 g ÷ 60.08 g/mol = 2584.88 mol

Number of moles of C taken: n₂ = w₂ ÷ m₂ = 79300 g ÷ 12.01 g/mol = 6602.83 mol

Actual ratio = n₁ ÷ n₂ = 2584.88 mol SiO₂ ÷ 6602.83 mol C = 0.39 mol SiO₂ ÷ 1 mol C

Since the stoichiometric ratio > actual ratio

Therefore, SiO₂ is the limiting reagent.

Now, the mass of SiO₂ in 1 mol = number of moles × molar mass = 1 mol × 60.08 g/mol = 60.08 g

the mass of Si in 1 mol = number of moles × molar mass = 1 mol × 28.08 g/mol = 28.08 g

So 28.08 g of Si is produced from 60.08 g SiO₂

Therefore, the amount of Si produced from 155300 g SiO₂ = 155300 g × 28.08 g ÷ 60.08 g = 72583.62 g = 72.58 kg

Therefore, the theoretical yield of Si = 72.58 kg

Actual yield of Si = 66.2 kg

Therefore, Percent Yield = Actual yield ÷ Theoretical yield × 100 = 66.2 kg ÷ 72.58 kg × 100 = 91.2 %

3 0

3 years ago

Que. 1. Gallium has 2 naturally occuring Isotopes with mass numbers 69 & 71 respectively. What is the percentage abundance o

IgorC [24]

Isotopes are atoms of the same element that have different masses. The relative atomic mass (am) is a weighted average that takes into account the abundance of each isotope. We can calculate the relative atomic mass using the following expression.

$am = \frac{\Sigma m_i \times ab_i}{100}$

where,

mi: mass of each isotope

abi: percent abundance of each isotope

For Gallium,

$70.59 amu = \frac{69 amu\ x + 71 amu\ y}{100}$ [1]

where "x" and "y" are the unknown abundances.

We also know that the sum of both abundances must be 100%.

x + y = 100

y = 100 - x [2]

If we replace [2] in [1], we get

$70.59 amu = \frac{69 amu\ x + 71 amu\ (100-x)}{100} \\7059 amu = -2 amu\ x + 7100amu \\x = 20.5$

Then, in [2]

y = 100 - x = 100 - 20.5 = 79.5

In conclusion, Ga-69 has an abundance of 20.5% and Ga-71 has an abundance of 79.5%.

You can learn more about isotopes in: brainly.com/question/21536220?referrer=searchResults

7 0

3 years ago

How many moles are in 230 grams of calcium phosphate

alexgriva [62]

Answer: 0.74 moles

Explanation:

The first step is to figure out the chemical formula for calcium phosphate. Since we know that calcium is a metal, this will be an ionic bond. Calcium is written as Ca and has a charge of +2. Phosphate is written as PO4 with a charge of -3. To come up with the subscripts for this formula, cross the charges. That means that you will get $Ca_{3} (PO_{4} )_{2}$ .

Next, calculate how many grams one molecule of calcium is. Calcium has an atomic weight of 40, and there are 3 molecules of calcium, so 40 x 3 = 120. Phosphorus has an atomic weight of 31, and there are 2 molecules of phosphorus, so 31 x 2 = 62. Oxygen has an atomic weight of 16, and there are 8 molecules of oxygen, so 16 x 8 = 128. Adding all of those together gives you 310 g.

Now, using stoichiometry, we can figure out the question. We know that there are 230 grams. We also know that one mole weighs 310 g. If you divide 230 by 310, you will get your answer, which is 0.74 moles.

3 0

3 years ago

Read 2 more answers