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3 years ago

According to the law of conservation of matter, what number must be the same on each side of a chemical equation?

Physics

1 answer:

olga2289 [7]3 years ago

7 0

Answer:

4. The number of atoms of each element

Explanation:

Why is 1 wrong?

The number of substances (i.e. number of mols of substances) do not have to be the same. For instance, 2 mol of water reacts with 1 mol of oxygen to form 2 mol of water. Obviously the numer of substances is not conserved. Thus, it isn't a requirement.

Why is 2 wrong?

The number of chemical symbols do not mean anything. They do not tell us anything about the quantity of matter, they only tell us about the elements that are involved in the reaction.

Why is 3 wrong?

Once again, the number of chemical formulas are meaningless.

Why is 4 correct?

The number of atoms are always conserved as atoms cannot be broken or created.

Possible confusion...

The number of atoms are always conserved but the number of molecules may not always be conserved.

Why? As 2 atoms may be a molecule on the reactant side and 4 atoms may become a molecule on the product size, causing the number of molecules to reduce by half, while the number of atoms remain constant.

Hope that makes sense!

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Consider a system of a cliff diver and the earth. the gravitational potential energy of the system decreases by 28,000 j as the

olga2289 [7]

The decrease in gravitational potential energy of the system is given by

$\Delta U = (mg) \Delta h$

where

m is the mass, g is the gravitational acceleration, and $\Delta h$ is the variation of height of the system.

$(mg)$ also corresponds to the weight of the diver, therefore if we rearrange the equation and we use $\Delta U=28000 J$ and $\Delta h=32.0 m$ , we can find her weight:

$mg=\frac{\Delta U}{\Delta h}=\frac{28000 J}{32 m}=875 N$

5 0

4 years ago

A bullet of mass m and speed v is fired at, hits and passes completely through a pendulum bob of mass M on the end of a stiff ro

dexar [7]

Required value of initial speed of the bullet be ( 4M/m)√(gL).

Given parameters:

Mass of the bullet =m.

Mass of the bob of the pendulum = M.

speed of the bullet before collision = v

Speed of the bullet after collision = v/2.

Length of the pendulum stiff rod = L.

Let speed transmitted to the pendulum be u.

Using principle of conservation of momentum:

mv = Mu + mv/2

⇒ Mu = mv/2

⇒ u = (m/M)v/2

We know that: to make the bob over the top of the trajectory without falling backward in its circular path, required speed be = √(4gL). [ where g = acceleration due to gravity]

To be minimum initial speed the bullet must have in order for the pendulum bob to just barely swing through a complete vertical circle:

u = √(4gL)

⇒ (m/M)v/2 = √(4gL)

⇒ v =( 4M/m)√(gL).

Hence, minimum required speed of the bullet be ( 4M/m)√(gL).

Learn more about speed here:

brainly.com/question/28224010

#SPJ1

7 0

1 year ago

Kirchhoff's Rules When applying Kirchhoff's rules, one of the essential steps is to mark each resistor with plus and minus signs

luda_lava [24]

Answer:

d. R4

Explanation:

Generally, the flow of current is always from the positive sign to the negative sign. In the resistors R1, R2, and R3, the direction of flow of current is from the positive sign to the negative sign. However, in the resistor R4, the direction of the flow of current is different from the conventional method. Therefore, the resistor R4 is marked wrongly.

8 0

3 years ago

An element's atomic number is the

Zepler [3.9K]

the atomic number of a chemical element (also known as its proton number) is the number of protons found in the nucleus of an atom of that element, and therefore identical to the charge number of the nucleus.

Hope this helped

8 0

3 years ago

3. Calculate the momentum of a 1200kg car with a velocity of 25m/s.

antiseptic1488 [7]

momm=massxvelocity

momm=1200x2.5=120x25=600x5=3000kgm/s

4 0

3 years ago