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4 years ago

Alexandria became the center for _____. its science

1 answer:

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Alexandria became the center for Hellenistic scholarship and culture. It was a great revolution in learning during this era as Alexandria had a library filled with books and important documents which were copied and even stolen. Over 500,000 titles were present in Alexandria's library.

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Which of the following statements BEST explains why ball-and-socket joints have the greatest range of motion?

galina1969 [7]

Answer:

its d on edge c:

5 0

3 years ago

Computes average speed when a person walk for 1 minute at speed of 1.5 m/s and another 1 minute at speed of 3.5 m/s along a stra

Vinvika [58]

Answer:

2.5 m/s

Explanation:

(60*1.5+60*3.5)/120=2.5

(1.5+3.5)/2=2.5

3 0

3 years ago

When you trip, your foot stops, but your body continues to move forward. Which statement best explains why this happens?(1 point

RideAnS [48]

The statement which best explains why when you trip, your foot stops, but your body continues to move forward is: A. An unbalanced force stops your foot but does not act on the rest of your body.

A force can be defined as a push or pull of an object or a physical body, which typically results in a change of motion due to the interaction of the object with another.

In Physics, there are two (2) main types of force and these are:

Balanced force.

Unbalanced force.

An unbalanced force occurs when two or more forces acting on an object or a physical body are not equal in magnitude and as such, it typically results in a change of motion.

In conclusion, when you trip, your foot stops, but your body continues to move forward because an unbalanced force stops your foot but doesn't act on the other part of your body.

6 0

3 years ago

Read 2 more answers

It took a crew 3 h 20 min to row 5 km upstream and back again. if the rate of flow of the stream was 2 km/h, what was the rowing

Basile [38]

Suppose rowing speed is V km/s.

So, upstream speed = V-2

Downstream speed = V+ 2

Total time is taken 3 h 20 min to cover up and down journey of 5 km.

So, total time = upstream time + downstream time

$3. 3 \ hours = \frac{5 km}{ V- 2} + \frac{5 km}{V+2} \\\\\ 3.3 (V^2-2^2) = 10V\\\\V^2- 4-3V= 0$

$V^2 -4V+V -4=0 \\\\\ V( V-4) +1 (V-4)=0$

$V= 4 km/h$ and $V= -1 \ km/h$ , we take only positive velocity.

Thus, the the rowing speed of the crew in still water is 1 km/s.

8 0

3 years ago

Find the energy of one quantum of microwave radiation with frequency 4 GHz and with 500 GHz .

REY [17]

Answer:

1. $1.65*10^{-5} eV$ and $2.07*10^{-3}eV$ 2. $2.10*10^{-7}m$

Explanation:

The energy of a photon is given by the so-called Planck-Einstein relation:

$E=fh=\frac{ch}{\lambda}$

where E is the energy, f the frequency, $\lambda$ the wavelength, c the speed of light and h the planck constant

So, we have:

$E=fh\\E=(4*10^9Hz)(4.136*10^{-15}eV*s)=1.65*10^{-5} eV\\$

And:

$E=fh\\E=(5*10^{11}Hz)(4.136*10^{-15}eV*s)=2.07*10^{-3} eV\\$

2. The work function is the amount of energy required to remove an electron from the material. Therefore the kinetic energy of the photoelectrons will be the energy of the electromagnetic radiation minus the work function:

$K=E-W$

Where K is the kinetic energy and W the work function, for copper W=4.7eV

Rewriting for $\lambda$ :

$E=K+W\\\frac{ch}{\lambda}=K+W\\\lambda=\frac{ch}{K+W}\\\lambda=\frac{(3*10^8m/s)4.136*10^{-15}eV}{1.2eV+4.7eV}=2.10*10^{-7}m$

This wavelength corresponds to the ultraviolet range

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3 years ago