An object is accelerating at -6.2 m/s? It comes to a stop after 2.0 seconds. What was its initial velocity?
1 answer:
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Answer:
a. The force of gravity on the droplet is approximately 4.606 × 10⁻¹⁴ Newtons
b. The electric force that balances the force of gravity is approximately -4.606 × 10⁻¹⁴ Newtons
c. The excess charge is approximately -1.439375 × 10⁻¹⁸ C
d. There are approximately 9 excess electrons on the droplet
Explanation:
The parameters of the Millikan experiment are;
The mass of the droplet, m = 4.7 × 10⁻¹⁵ kg
The electric field in which the droplet floats, E = 3.20 × 10⁴ N/C
a. The force of gravity on the droplet, F = The weight of the droplet, W = m × g
Where;
g = The acceleration due to gravity ≈ 9.8 m/s²
W = 4.7 × 10⁻¹⁵ kg × 9.8 m/s² = 4.606 × 10⁻¹⁴ Newtons
∴ The force of gravity on the droplet = W = 4.606 × 10⁻¹⁴ Newtons
b. The electric force that balances the force of gravity, = -W = -4.606 × 10⁻¹⁴ Newtons
c. The excess charge is given as follows;
= q·E
∴ The electric force that balances the force of gravity, = q·E = -4.606 × 10⁻¹⁴ N
q·E = -4.606 × 10⁻¹⁴ N
q = -4.606 × 10⁻¹⁴ N/E
∴ q = -4.606 × 10⁻¹⁴ N/(3.20 × 10⁴ N/C) ≈ -1.439375 × 10⁻¹⁸ C
The excess charge, q ≈ -1.439375 × 10⁻¹⁸ C
d. The charge of one electron, e = 1.602176634 × 10⁻¹⁹C
The number of excess electrons in the droplet, n, is given as follows;
n = 1.439375 × 10⁻¹⁸ C/(1.602176634 × 10⁻¹⁹C) = 8.98387212405 electrons
∴ n ≈ 9 electrons.
Answer:
- The work made by the gas is 7475.69 joules
- The heat absorbed is 7475.69 joules
Explanation:
<h3>Work</h3>We know that the differential work made by the gas its defined as:
We can solve this by integration:
but, first, we need to find the dependence of Pressure with Volume. For this, we can use the ideal gas law
This give us
As n, R and T are constants
But the volume is:
Now, lets use the value from the problem.
The temperature its:
The ideal gas constant:
So:
We know that, for an ideal gas, the energy is:
where its the internal energy of the gas. As the temperature its constant, we know that the gas must have the energy is constant.
By the first law of thermodynamics, we know
where is the Work made by the gas (please, be careful with this sign convention, its not always the same.)
So: