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3 years ago

9

At archery practice, Vladimir tests a bow and arrow he has recently designed. He is able to accelerate a 24.0-g arrow at an aver

age rate of 70.0 m/s^2. What is the bows average force on the arrow

1 answer:

Whitepunk [10]3 years ago

7 0

Answer: A

1.68 N

Explanation:

F = ma = 0.024(70.0) = 1.68 N

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Bob is investigating whether the density of water changes with temperature. Which of the following variables should he change in

LekaFEV [45]

Answer:

temperature of the water

Explanation:

Density is defied as mass divided by the volume. To investigate how the density of water change with temperature, Bob have the change the temperature and read the volume and mass of the investigated sample.

Even if there is a different salt content between booted water or tap water and have an influence on the density (compared with pure water), this difference is not so big so the change in density with temperature can be determined. Considering that the experiment do not require extreme accuracy, any type of water may be used (bottled water of tap water).

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4 years ago

What is the amount of aluminum chloride produced from 40 moles of aluminum and excess chlorine?

Marrrta [24]

Answer:

is it 26.98

Explanation:

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3 years ago

What happens at the melting point temperature of a substance?

iren2701 [21]

Answer:

C

Explanation:

Melting point, temperature at which the solid and liquid forms of a pure substance can exist in equilibrium. As heat is applied to a solid, its temperature will increase until the melting point is reached. More heat then will convert the solid into a liquid with no temperature change.

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3 years ago

Two 10g blocks, one of copper and one of iron, were heated from 300 K to 400K (a temperature difference of 100 K).

12345 [234]

1) 385 J

2) 450 J

Explanation:

1)

The amount of energy that must be absorbed by a certain substance in order to increase its temperature by $\Delta T$ is given by the equation:

$Q=mC\Delta T$

where

m is the mass of the substance

C is its specific heat capacity

$\Delta T$ is the increase in temperature of the substance

For the block of copper in this problem, we have:

m = 10 g is the mass

$C=0.385 J/gK$ is the specific heat capacity of copper

$\Delta T=400-300 = 100 K$ is the change in temperature

So, the energy absorbed by the block of copper is

$Q=(10)(0.385)(100)=385 J$

2)

Similarly for the block of iron, the energy absorbed by the iron is given by

$Q=mC\Delta T$

where

m is the mass of the block of iron

C is its specific heat capacity of iron

$\Delta T$ is the increase in temperature of the block

Here we have:

m = 10 g is the mass of the block

$C=0.450 J/gK$ is the specific heat capacity of iron

$\Delta T=400-300 = 100 K$ is the change in temperature

So, the energy absorbed by the block of iron is

$Q=(10)(0.450)(100)=450 J$

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3 years ago

The concentration of hydroxide ions is less than the concentration of hydronium ions for acidic solutions. True False

wolverine [178]

Answer:

True

Explanation:

It's true because the pH is a measure of how basic or acid a solution is. In an acidic medium, the pH scales goes from 0 to 7. While in a basic medium goes from 7 to 14. The lower the pH value of the most acid the solution is.

1. The expression pH = -log(molar concentration of hydronium) allow to calculate the pH of a solution.

2. On the other hand, the expression pOH = -log(molar concentration of hydroxide) allow to determine the pOH of a solution.

The values of pH and pOH always obey the following expression:

pH + pOH = 14

Thus if for instance the pH becomes smaller the pOH must become bigger in order to fulfill the equation. Which means that the concentration of hydronium ions is greater than the hydroxide concentration.

For example, in an acidic medium:

if pH= 3, pOH= 11

In this case the molar concentration of hydronium is 0,001M. And the molar concentration of hydroxide ions is just 0,00000000001M.

4 0

3 years ago

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