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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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You have just landed on Planet X. You release a 100-g ball from rest from a height of 10.0 m and measure that it takes 3.40 s to

Nana76 [90]

Answer:

w = 0.173 N

Explanation:

The weigh of any object is computed by multiplying its mass to the acceleration of gravity, so we need to find the gravity on that planet in order to compute the weigh we want.

The ball has a mass of 0.1 kg and its released from a height of 10 m, therefore it is in a free fall motion with gravity acting as a constant acceleration on the body, we can use the equations for free fall movement in order to determine the value for this acceleration:

y(t) = v_0 * t + y_0 - 0.5 * g * t^2

y(t) is the position in the end of the movement, when t = 3.4 s, so y(t) = 0 m.

v_0 is the initial velocity, in this case v_0 = 0 m/s.

y_0 is the initial position of the ball, in this case it is 10 m.

g is the gravity that we want to know.

Applying these values in the equation we have:

0 = 0*(3.4) + 10 - 0.5*g*(3.4)^2

0 = 10 - 0.5*11.56*g

0 = 10 -5.78*g

5.78*g = 10

g = 1.73 m/s^2

Then we can use this value to find out the weigh of the ball in that planet:

w = g*m = 0.1*1.73 = 0.173 N

6 0

4 years ago

Problem 9: Suppose you wanted to charge an initially uncharged 85 pF capacitor through a 75 MΩ resistor to 90.0% of its final vo

Bingel [31]

Answer:

$t=14.678\times 10^{-3}s$

Explanation:

Given:

Capacitance, C = 85 pF = 85 × 10⁻¹² F

Resistance, R = 75 MΩ = 75×10⁶Ω

Charge in capacitor at any time 't' is given as:

$Q=Q_o(1-e^{-\frac{t}{RC}})$

where,

Q₀ = Maximum charge = CE

E = Initial voltage

t = time

also, Q = CV

V= Final voltage = 90% of E = 0.9E

thus, we have

$C\times 0.9E=CE(1-e^{-\frac{t}{75\times 10^6\ \times\ 85\times 10^{-12}}})$

$0.9=1-e^{-\frac{t}{75\times 10^6\ \times\ 85\times 10^{-12}}}$

$e^{-\frac{t}{75\times 10^6\ \times\ 85\times 10^{-12}}}=1-0.9=0.1$

taking log both sides, we get

$ln(e^{-\frac{t}{75\times 10^6\ \times\ 85\times 10^{-12}}})=ln(0.1)=ln(\frac{1}{10})$

$-\frac{t}{75\times 10^6\ \times\ 85\times 10^{-12}}=-ln(10)$

$t=75\times 10^6\ \times\ 85\times 10^{-12}\times ln{10}$

$t=14.678\times 10^{-3}s$

3 0

3 years ago

Which is an example of an unintentional injury? A student decides to cut herself. Two people have a domestic dispute that leads

slavikrds [6]

I think its the last one, a student slips on the ice in front of school and sprains his ankle. An example of a natural fiber could be cotton B.

7 0

3 years ago

The driver of a car travels at 90 km / h, observes some children playing on the road 50 m away, and applies the brakes, managing

Orlov [11]

Answer:

13,750 N

Yes

Explanation:

Given:

v₀ = 90 km/h = 25 m/s

v = 0 m/s

t = 4 s

Find: a and Δx

a = Δv / Δt

a = (0 m/s − 25 m/s) / (4 s)

a = -6.25 m/s²

F = ma

F = (2200 kg) (-6.25 m/s²)

F = -13,750 N

Δx = ½ (v + v₀) t

Δx = ½ (0 m/s + 25 m/s) (4 s)

Δx = 50 m

6 0

3 years ago

When a transformer is step down then

Vera_Pavlovna [14]

Answer:

Hey!

Your answer should be D!

Explanation:

In a transformer Np / Ns is called the voltage ratio. If Ns is less than Np then Vs is less than Vp. This is called a step-down transformer as the voltage is reduced.

(source from google.com!)

3 0

3 years ago