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2 years ago

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I will give brainliest to the best answer! I don’t understand vectors. This whole sheet is confusing me and i’m very behind, ple

ase help!!

1 answer:

Rudik [331]2 years ago

4 0

Explanation:

1. To graphically add vectors, use the tail-to-tip method. Draw the first vector (it doesn't matter which), then draw the second vector where the first vector ends. The resultant vector is from the tail of the first vector to the tip of the second vector.

This graph shows two ways to get the resultant: A + B or B + A.

desmos.com/calculator/bqhcclhhqc

2. To algebraically add vectors, split each vector into x and y components.

Aₓ = 5.0 cos 45 = 3.5

Aᵧ = 5.0 sin 45 = 3.5

Bₓ = 2.0 cos 180 = -2.0

Bᵧ = 5.0 sin 180 = 0

The components of the resultant vector are the sums of the components of A and B.

Cₓ = 3.5 + -2.0 = 1.5

Cᵧ = 3.5 + 0 = 3.5

The magnitude of the resultant vector is found with Pythagorean theorem, and the direction is found with tangent.

C = √(Cₓ² + Cᵧ²) ≈ 3.9 m/s

θ = atan(Cᵧ / Cₓ) ≈ 67°

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(a) What is the cost of heating a hot tub containing 1440 kg of water from 10.0°C to 40.0°C, assuming 75.0% efficiency to take h

BaLLatris [955]

Answer:

a) $E = 6.024\,USD$ , For m kilograms, it is 4184m J., 3600000 joules, b) $i = 88.200\,A$

Explanation:

a) The amount of heat needed to warm water is given by the following expression:

$Q_{needed} = m_{w}\cdot c_{w}\cdot (T_{f}-T_{i})$

Where:

$m_{w}$ - Mass of water, measured in kilograms.

$c_{w}$ - Specific heat of water, measured in $\frac{J}{kg\cdot ^{\circ}C}$ .

$T_{f}$ , $T_{i}$ - Initial and final temperatures, measured in $^{\circ}C$ .

Then,

$Q_{needed} = (1440\,kg)\cdot \left(4184\,\frac{J}{kg\cdot ^{\circ}C} \right)\cdot (40^{\circ}C - 10^{\circ}C)$

$Q_{needed} = 180748800\,J$

The energy needed in kilowatt-hours is:

$Q_{needed} = 180748800\,J\times \left(\frac{1}{3600000}\,\frac{kWh}{J} \right)$

$Q_{needed} = 50.208\,kWh$

The electric energy required to heat up the water is:

$E = \frac{50.208\,kWh}{0.75}$

$E = 66.944\,kWh$

Lastly, the cost of heating a hot tub is: (USD - US dollars)

$E = (66.944\,kWh)\cdot \left(0.09\,\frac{USD}{kWh} \right)$

$E = 6.024\,USD$

The heat needed to raise the temperature a degree of a kilogram of water is 4184 J. For m kilograms, it is 4184m J. Besides, a kilowatt-hour is equal to 3600000 joules.

b) The current required for the electric heater is:

$i = \frac{Q_{needed}}{\eta \cdot \Delta V \cdot \Delta t}$

$i = \frac{180748800\,J}{0.75\cdot (220\,V)\cdot (3.45\,h)\cdot \left(3600\,\frac{s}{h} \right)}$

$i = 88.200\,A$

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3 years ago

Why has the atomic model changed over time

inysia [295]

The first model of the atom was developed by JJ Thomson in 1904, who thought that atoms were composed purely of negatively charged electrons. This model was known as the 'plum pudding' model.

This theory was then disproved by Ernest Rutherford and the gold foil experiment in 1911, where Rutherford shot alpha particles at gold foil, and noticed that some went through and some bounced back, implying the existence of a positive nucleus.

In 1913, Niels Bohr proposed a model of the atom where the electrons were contained within quantized shells that orbited the nucleus. This was because it was impossible for the cloud of negative electrons proposed by Rutherford to exist, as the negative electrons would be drawn to the positive nucleus, and the atom would collapse in on itself.

In 1926, the Austrian physicist Erwin Schrödinger created a quantum mechanical model of the atom by combining the equations for the behavior of waves with the de Broglie equation to generate a mathematical model for the distribution of electrons in an atom.

However the model used today is closest to the Bohr model of the atom, using the quantized shells to contain the electrons.

For more info:

http://chemistry.about.com/od/chemistryglossary/a/debroglieeqdef.htm

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3 years ago

The toy car is about 3 inches long is an example of a ?

balandron [24]

Answer:

a quantitative observation because it includes numerical data

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3 years ago

What is the direction of the magnetic field if an electron moving in the positive x direction experiences a magnetic force in th

Alex787 [66]

Given :

An electron moving in the positive x direction experiences a magnetic force in the positive z direction.

To Find :

The direction of the magnetic field.

Solution :

We know, force is given by :

$\vec{F}=q(\vec{v}\times \vec{B)}$

Here, q = -e.

$\vec{F}=(-e)(\vec{v}\times \vec{B)}\\\\\hat{k}=(-e)(\hat{i}\times \vec{B})$

Now, for above condition to satisfy :

$\hat{i}\times \vec{B}=-\hat{k}$

So, $\vec{B}=-\hat{j}$

Therefore, direction of magnetic field is negative y direction.

Hence, this is the required solution.

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3 years ago

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Good morning, Jesusperez7!

Semi-conductors are materials that have insulator and conductor properties.

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