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3 years ago

How Fast Is Lightning?

1 answer:

8 0

The return stroke (the current that cause the visible flash) moves upward at a speed of about 320,000,000 ft per second or about 220,000,000 miles per hour (about 1/3 the speed of light).

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Mariah trained for months leading up to the marathon, and she won. After seeing this, her friends and family would describe her

alexandr402 [8]

Answer:

Mariah trained for months leading up to the marathon and won. Her sole motivation was that after seeing her winning the marathon, her friends and family would call her as motivated and athletic. It means that Mariah wanted to fulfill her esteem needs.

Explanation:

According to Abraham Maslow:

Safety needs includes the personal security, the safety of health, resources and property. etc.

Physiological needs falls at the lowest level of basic needs. It includes food, water, rest. etc which are necessary for an individual's survival.

Esteem includes the need of respect and self-confidence.

Cognitive needs includes the desire of knowledge, to know things, to know what is happening and why is it happening around you.

In Mariah's case, she needed respect and motivation and thus she was trying to fulfill her esteem needs by winning the marathon.

8 0

3 years ago

Read 2 more answers

Lasers are now used in eye surgery. Given the wavelength of a certain laser is 514 nm and the power of the laser is 1.1 W, how m

Leno4ka [110]

Answer: $1.593*10^{17} photons$ released if the laser is used 0.056 s during the surgery

Explanation:

First, you have to calculate the energy of each photon according to Einstein's theoty, given by:

$E =\frac{hc}{\lambda}$

Where $\lambda$ is the wavelength, $h$ is the Planck's constant and $h$ is the speed of light

$h = 6.626*10^{-34} \frac{m^{2} kg }{s}$ -> Planck's constant

$c = 3*10^{8} \frac{m}{s}$ -> Speed of light

So, replacing in the equation:

$E =\frac{ 6.626*10^{-34} \frac{m^{2} kg }{s}*3*10^{8} \frac{m}{s}}{514*10^-9 m}$

Then, the energy of each released photon by the laser is:

$E = 3.867*10^{-19} \frac{J}{photons}$

After, you do the inverse of the energy per phothon and as a result, you will have the number of photons in a Joule of energy:

$\frac{1}{3.867*10^{-19}} = 2.586*10^{18} \frac{photons}{J}$

The power of the laser is 1.1 W, or 1.1 J/s, that means that you can calculate how many photons the laser realease every second:

$2.586*10^{18}\frac{photons}{J} * 1.1 \frac{J}{s} = 2.844*10^{18} \frac{photons}{s}$

And by doing a simple rule of three, if $2.844*10^{18} photons$ are released every second, then in 0.056 s:

$0.056 s*2.844*10^{18} \frac{photons}{s} = 1.593*10^{17} photons$ are released during the surgery

5 0

3 years ago

A 0.48 kg circus monkey is about to be shot from a cannon as part of his thrilling circus act. Draw a free body diagram labeling

Alenkinab [10]

What is it that you need help on?

6 0

2 years ago

You are testing a new amusement park roller coaster with an empty car with a mass 120 kg. One part of the track is a vertical lo

Kay [80]

Answer:

- 5436 J

Explanation:

mass of car, m = 120 kg

radius of loop, r = 12 m

velocity at the bottom (A) = Va = 25 m/s

Velocity at the top(B) = Vb = 8 m/s

Vertical distance from A to B = diameter of loop, h = 2 x 12 = 24 m

by use of Work energy theorem

Work done by all the forces = change in kinetic energy of the body

Work done by the force + Work done by the friction = Kinetic energy at B - kinetic energy at A

- m x g x h + Work done by friction = 0.5 x 120 x (Vb^2 - Va^2)

- 120 x 9.8 x 24 + Work done by friction = 60 x (64 - 625)

- 28224 + Work done by friction = - 33660

Work done by friction = -33660 + 28224 = - 5436 J

4 0

3 years ago

Using at least 3 to 4 complete content related sentences describe the first and second postulate of special relativity.

Andrew [12]

Nothing can travel faster than the speed of light. As such, perceptions of objects and time change as they approach light speed, but the laws of physics remain consistent regardless of speed. Objects will appear shortened and time will appear to slow down around an observer approaching near light speeds, but all quantities still exist as they did before and all causality is preserved, even if observers in different points or traveling at different speeds will report different things.

8 0

4 years ago

Read 2 more answers