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4 years ago

Which part(s) of the electromagnetic spectrum are visible to humans?

Physics

1 answer:

jarptica [38.1K]4 years ago

4 0

Color aka the visible light spectrum

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A 4.87-kg ball of clay is thrown downward from a height of 3.21 m with a speed of 5.21 m/s onto a spring with k = 1570 N/m. The

Yuki888 [10]

Answer:

Approximately $0.560\; {\rm m}$ , assuming that:

the height of $3.21\; {\rm m}$ refers to the distance between the clay and the top of the uncompressed spring.
air resistance on the clay sphere is negligible,
the gravitational field strength is $g = 9.81\; {\rm m\cdot s^{-2}}$ , and
the clay sphere did not deform.

Explanation:

Notations:

Let $k$ denote the spring constant of the spring.
Let $m$ denote the mass of the clay sphere.
Let $v$ denote the initial speed of the spring.
Let $g$ denote the gravitational field strength.
Let $h$ denote the initial vertical distance between the clay and the top of the uncompressed spring.

Let $x$ denote the maximum compression of the spring- the only unknown quantity in this question.

After being compressed by a displacement of $x$ , the elastic potential energy $\text{PE}_{\text{spring}}$ in this spring would be:

$\displaystyle \text{PE}_{\text{spring}} = \frac{1}{2}\, k\, x^{2}$ .

The initial kinetic energy $\text{KE}$ of the clay sphere was:

$\displaystyle \text{KE} = \frac{1}{2}\, m \, v^{2}$ .

When the spring is at the maximum compression:

The clay sphere would be right on top of the spring.
The top of the spring would be below the original position (when the spring was uncompressed) by $x$ .
The initial position of the clay sphere, however, is above the original position of the top of the spring by $h = 3.21\; {\rm m}$ .

Thus, the initial position of the clay sphere ( $h = 3.21\; {\rm m}$ above the top of the uncompressed spring) would be above the max-compression position of the clay sphere by $(h + x)$ .

The gravitational potential energy involved would be:

$\text{GPE} = m\, g\, (h + x)$ .

No mechanical energy would be lost under the assumptions listed above. Thus:

$\text{PE}_\text{spring} = \text{KE} + \text{GPE}$ .

$\displaystyle \frac{1}{2}\, k\, x^{2} = \frac{1}{2}\, m\, v^{2} + m\, g\, (h + x)$ .

Rearrange this equation to obtain a quadratic equation about the only unknown, $x$ :

$\displaystyle \frac{1}{2}\, k\, x^{2} - m\, g\, x - \left[\left(\frac{1}{2}\, m\, v^{2}\right)+ (m\, g\, h)\right] = 0$ .

Substitute in $k = 1570\; {\rm N \cdot m^{-1}}$ , $m = 4.87\; {\rm kg}$ , $v = 5.21\; {\rm m\cdot s^{-1}}$ , $g = 9.81\; {\rm m \cdot s^{-2}}$ , and $h = 3.21\; {\rm m}$ . Let the unit of $x$ be meters.

$785\, x^{2} - 47.775\, x - 219.453 \approx 0$ (Rounded. The unit of both sides of this equation is joules.)

Solve using the quadratic formula given that $x \ge 0$ :

$\begin{aligned}x &\approx \frac{-(-47.775) + \sqrt{(-47.775)^{2} - 4 \times 785 \times (-219.453)}}{2 \times 785} \\ &\approx 0.560\; {\rm m}\end{aligned}$ .

(The other root is negative and is thus invalid.)

Hence, the maximum compression of this spring would be approximately $0.560\; {\rm m}$ .

5 0

3 years ago

The electric potential inside a parallel-plate capacitor __________.

tresset_1 [31]

Answer:

$\Delta V=\frac{Q d}{A \epsilon_0}$

Explanation:

for the calculation of the electric potential inside a parallel plate capacitor you can use the formula for the electric field inside the capacitor.

$\Delta V=V(d)-V(0)=\int_0^dEdx$

where d is the distance between plates and E is the electric field, which is given by:

$E=\frac{\sigma}{\epsilon_0}$

By replacing you obtain:

$\Delta V=E\int_0^ddx=Ed=\frac{\sigma d}{\epsilon_0}=\frac{Qd}{A\epsilon_0}$

where Q is the charge stored by the capacitor and A is the area of the plates.

hence, the answer is Qd/Ae0

4 0

3 years ago

A force of 500 N is used to slide a box across a smooth surface; the box moved 5 m in 1.2 seconds. What power is used?

Katen [24]

F = 500N
S = 5m
T = 1.2s
----------------------------------
P = ?

We can use formula P = F * V, just because it was a smooth slide we can assume that average speed was V = S/T = 5 / 1.2 = 50/12

So the final answer would be:

P = F * V = 500 * 50/12

Are you sure those are correct numbers? The answer don't look nice :D

8 0

3 years ago

Read 2 more answers

Henry ran a 100 m race. Use the graph to answer the following:

horrorfan [7]

Using the graph, which describes how Henry ran the 100m race;

a) It takes Henry 20seconds to run 100m

b) Henry's average speed over the race is; 5m/s.

According to the linear graph which describes the distance ran by Henry during the 100m race as a function of time.

a) Since the distance from start ran by Henry is plotted on the vertical axis, and the time is plotted on the horizontal axis;

To determine how long it took Henry to run 100m; The point corresponding to 100m is traced downward from the line of the graph and we find out that;

It takes Henry 20seconds to run 100m

b) Henry's average speed over the race is simply;

The slope of the distance-time graph.

Therefore,

Average speed = (100-0)/(20-0)

Average speed = 100/20

Average speed = 5m/s.

Therefore, Henry's average speed over the race is; 5m/s.

brainly.com/question/22125199

6 0

2 years ago

What qualifications do you need to be a research scientist?

Vedmedyk [2.9K]

The qualifications boil down to: College education.

In most university or industrial research organizations, you might be able to work there as a member of the team who doesn't get much pay or much respect, with research going on all around you directed by other people, after you've gotten you Master's degree.

But you really don't have a shot at leading anything, or having much to say about what's being researched or how, until you have a PhD degree in the field where you'd like to do the research.

(Did I mention how proud I was to be present about 6 weeks ago, in a land far away, when my daughter was awarded a PhD degree in Molecular Biology ? I didn't want to let you get away without hearing about that.)

5 0

3 years ago