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zvonat [6]
3 years ago
15

Can a chemical change be undone?​

Physics
2 answers:
Ksivusya [100]3 years ago
6 0

Answer:

no

Explanation:

because it will bind together in the molecular level

Zigmanuir [339]3 years ago
3 0
Because chemical changes result in different substances, they often cannot be undone. Some chemical changes can be reversed, but only by other chemical changes.
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A 1200-kg car initially at rest undergoes constant acceleration for 9.4 s, reaching a speed of 11 m/s. It then collides with a s
Natalka [10]

To solve this problem we will apply the principle of conservation of energy and the definition of kinematic energy as half the product between mass and squared velocity. So,

KE_i = KE_f

KE_f = \frac{1}{2} mv^2

Here,

m = Mass

V = Velocity

Replacing,

KE_f = \frac{1}{2} (12000)(11)^2

KE_f = 72600J

Therefore the  final kinetic energy of the two car system is 72.6kJ

8 0
3 years ago
Potassium is a crucial element for the healthy operation of the human
Degger [83]

Answer:

1

  The mass of the Potassium-40 is  m_{40}} = 2.88*10^{-6} kg

2

  The Dose per year in Sieverts is   Dose_s = 26.4 *10^{-10}

Explanation:

From the question we are told that

   The isotopes of potassium in the body are Potassium-39, Potassium-40, and Potassium- 41

    Their abundance is 93.26%, 0.012% and 6.728%

   The mass of potassium contained in human body is  m = 3.0 g = \frac{3}{1000} = 0.0003 \ kg per kg of the body

    The mass of the first body is  m_1 = 80 \ kg

Now the mass of  potassium  in this body is mathematically evaluated as

       m_p =  m * m_1

substituting value

       m_p =  80  * 0.0003

      m_p  =0.024 kg

The amount of Potassium-40 present  is mathematically evaluated as

      m_{40}} =0.012% * 0.024

      m_{40}} = \frac{0.012}{100}  * 0.024

      m_{40}} = 2.88*10^{-6} kg

The dose of energy absorbed per year is mathematically represented as

          Dose  = \frac{E}{m_1}

Where E is the energy absorbed which is given as E = 1.10 MeV = 1.10 * 10^6 * 1.602*10^{-19}

    Substituting value

            Dose  = \frac{ 1.10 * 10^6 * 1.602*10^{-19}}{80}

            Dose  = 22*10^{-10} J/kg

The Dose in Sieverts is evaluated as

       Dose_s = REB * Dose

       Dose_s = 1.2 * 22*10^{-10}

       Dose_s = 26.4 *10^{-10}

             

3 0
3 years ago
Nresistors, each having resistance equal to 1 2, are arranged in a circuit first in series and then in parallel. What is the rat
aleksandr82 [10.1K]

Answer:

option (b)

Explanation:

Let the resistance of each resistor is R.

In series combination,

The effective resistance is Rs.

rs = r + R + R + .... + n times = NR

Let V be the source of potential difference.

Power in series

Ps = v^2 / Rs = V^2 / NR ..... (1)

In parallel combination

the effective resistance is Rp

1 / Rp = 1 / R + 1 / R + .... + N times

1 / Rp = N / R

Rp = R / N

Power is parallel

Rp = v^2 / Rp = N V^2 / R    ..... (2)

Divide equation (1) by equation (2) we get

Ps / Pp = 1 / N^2

5 0
3 years ago
Which objects will likely have the smallest gravitational force between them?
DENIUS [597]

Answer:

A. Two tennis balls that are near each other  

Explanation:

The formula for gravitational force (F) between two objects is

F = \dfrac{Gm_{1}m_{2}}{d^{2} }

where m₁ and m₂ are the masses of the two objects, d is the distance between their centres, and G is the gravitational constant.

Thus, two objects that are far from each other will have a smaller gravitational force. We can eliminate Options C and D.

If the objects are at the same distance, those with the smaller mass will have a smaller force.

The mass of a tennis ball is 57 g.

The mass of a soccer ball is 430 g.

Two tennis balls that are near each other will have a smaller gravitational attraction.

3 0
3 years ago
if the amplitude of sine curve is 4 and the frequency is 1 with no phase shift, what is the function that descirbes this curve?
Vlada [557]

Answer:

y = 4 Sin (2πt)

Explanation:

Amplitude, A = 4

frequency, f = 1

Wave function is given by

y = A sinωt

where, ω is angular frequency

ω = 2 π f = 2 π x 1 = 2π

So, the desired wave function

y = 4 Sin (2πt)

8 0
3 years ago
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