A rock at the top of a 20 meter tall hill.The rock has a mass of 10 kg. How much potentail energy does it have?

The area of the brain involved with comprehension of speech is

PSYCHO15rus [73]

Wernicke's area is where comprehension of speech is

8 0

3 years ago

If a hockey player starts from rest and accelerates at a rate of 2.1 m/s2 how long does it take him to skate 30m

OLga [1]

Hello!

<span>Let us apply the time function of space, in the uniform uniform motion (UUM)
</span>
Formula: $S = S_{o} + V_{o}* t + a* \frac{t^2}{2}$

Data:
S (Final position) = 30 m
So (Initial Position) = 0 m
Vo (Initial velocity) = 0 m/s
t (time) = ? (in seconds)
a (acceleration) = 2.1 m/s²

Solving:
$S = S_{o} + V_{o}* t + a* \frac{t^2}{2}$
$30 = 0 + 0*t + 2.1* \frac{t^2}{2}$
$30 = \frac{2.1t^2}{2}$
$30*2 = 2.1t^2$
$60 = 2.1t^2$
$2.1t^2 = 60$
$t^2 = \frac{60}{2.1}$
$t^2 \approx 28.5$
$t \approx \sqrt{28.5}$
$\boxed{\boxed{t \approx 5.3\:s}}\end{array}}\qquad\quad\checkmark$

Answer:
<span>C. 5.3s</span>

5 0

4 years ago

Why do some astronomers object to the new definition of a planet that was adopted in 2006?

cestrela7 [59]

Answer:

A. New space missions show that Pluto is much larger than originally thought.

Explanation:

The new definition of a planet that was adopted in 2006, defined planet as an object that orbits the sun, with sufficient mass to be round, not a satellite of another object, and has removed debris and small objects from the area around its orbit.

This new definition of a planet that was adopted in 2006, classified Pluto as "dwarf planet", because Pluto meets planetary criteria except that it has not cleared debris from its orbital neighborhood.

However, new Horizons spacecraft flew by Pluto in 2015, revealed that Pluto is much larger than originally thought

Therefore, the correct option is "A"

A. New space missions show that Pluto is much larger than originally thought.

4 0

4 years ago

Based on the law of conservation of energy, how can we reasonably improve a machine’s ability to do work?

bagirrra123 [75]

Reduce friction because friction just makes things harder

5 0

3 years ago

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The n = 2 to n = 6 transition in the bohr hydrogen atom corresponds to the ________ of a photon with a wavelength of ________ nm

Colt1911 [192]

The energy levels of the hydrogen atom are quantized and their energy is given by the approximated formula
$E=- \frac{13.6}{n^2} [eV]$
where n is the number of the level.

In the transition from n=2 to n=6, the variation of energy is
$\Delta E=E(n=6)-E(n=2)=-13.6 ( \frac{1}{6^2}- \frac{1}{2^2} )[eV]=3.02 eV$
Since this variation is positive, it means that the system has gained energy, so it must have absorbed a photon.

The energy of photon absorbed is equal to this $\Delta E$ . Converting it into Joule,
$\Delta E=3.02 eV=4.84 \cdot 10^{-19}J$
The energy of the photon is
$E=hf$
where h is the Planck constant while f is its frequency. Writing $\Delta E=hf$ , we can write the frequency f of the photon:
$f= \frac{\Delta E}{h}= \frac{4.84 \cdot 10^{-19}J}{6.63 \cdot 10^{-34}m^2 kg/s}=7.29 \cdot 10^{14}Hz$

The photon travels at the speed of light, $c=3 \cdot 10^8 m/s$ , so its wavelength is
$\lambda = \frac{c}{f}= \frac{3 \cdot 10^8 m/s}{7.29 \cdot 10^{14}Hz}=4.11 \cdot 10^{-7}m=411 nm$

So, the initial sentence can be completed as:
The n = 2 to n = 6 transition in the bohr hydrogen atom corresponds to the "absorption" of a photon with a wavelength of "411" nm.

4 0

4 years ago

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