All categories

4 years ago

Which theory of the spread of human beings is supported most by modern evidence?

Physics

2 answers:

Virty [35]4 years ago

6 0

C. Out of Africa theory (APEX)

tigry1 [53]4 years ago

3 0

I think best answer would be A because it sound why better

You might be interested in

A heavy boy and a lightweight girl are balanced on a massless seesaw. If they both

Len [333]

Answer:

D. Nothing will happen; the seesaw will still be balanced.

Explanation:

D. Nothing will happen; the seesaw will still be balanced. Since both toruqes or momentums respect to the center have changed in the same amount (one-half their original distance) the seesaw will remain balanced, if the children change distance in a different amount then it will be out of balance

3 0

3 years ago

Read 2 more answers

Is a body which is moving in a negative direction but has a positive acceleration speeding up or slowing down?

melamori03 [73]

Answer:

An object with negative acceleration could be speeding up, and an object with positive acceleration could be slowing down.

Explanation:

hope this helps

have a great day/night

7 0

3 years ago

Why should we invest more money in renewable energy resources

oksian1 [2.3K]

Answer:

It is the smarter option.

Explanation:

Renewable energy is the cheapest source of new power generation for more than two-thirds of the world and has no fuel costs. It can reduce the economic burden of energy bills by eliminating fuel charges — especially when coupled with energy-efficiency upgrades in our homes and businesses.

3 0

3 years ago

10. A triply ionized beryllium atom is in the ground state. It absorbs energy and makes a transition to the n = 5 excited state.

Xelga [282]

Answer:

$\lambda=1282\ nm$

Explanation:

$E_n=-2.179\times 10^{-18}\times \frac{1}{n^2}\ Joules$

For transitions:

$Energy\ Difference,\ \Delta E= E_f-E_i =-2.179\times 10^{-18}(\frac{1}{n_f^2}-\frac{1}{n_i^2})\ J=2.179\times 10^{-18}(\frac{1}{n_i^2} - \dfrac{1}{n_f^2})\ J$

$\Delta E=2.179\times 10^{-18}(\frac{1}{n_i^2} - \dfrac{1}{n_f^2})\ J$

Also, $\Delta E=\frac {h\times c}{\lambda}$

Where,

h is Plank's constant having value $6.626\times 10^{-34}\ Js$

c is the speed of light having value $3\times 10^8\ m/s$

So,

$\frac {h\times c}{\lambda}=2.179\times 10^{-18}(|\frac{1}{n_i^2} - \dfrac{1}{n_f^2}|)\ J$

$\lambda=\frac {6.626\times 10^{-34}\times 3\times 10^8}{{2.179\times 10^{-18}}\times (|\frac{1}{n_i^2} - \dfrac{1}{n_f^2}|)}\ m$

So,

$\lambda=\frac {6.626\times 10^{-34}\times 3\times 10^8}{{2.179\times 10^{-18}}\times (|\frac{1}{n_i^2} - \dfrac{1}{n_f^2}|)}\ m$

Given, $n_i=5\ and\ n_f=3$

$\lambda=\frac{6.626\times 10^{-34}\times 3\times 10^8}{{2.179\times 10^{-18}}\times (\frac{1}{5^2} - \dfrac{1}{3^2})}\ m$

$\lambda=\frac{10^{-26}\times \:19.878}{10^{-18}\times \:2.179\left(|\frac{1}{25}-\frac{1}{9}\right)|}\ m$

$\lambda=\frac{19.878}{10^8\times \:2.179\left(|-\frac{16}{225}\right|)}\ m$

$\lambda= 1.2828\times10^{-6}$

1 m = 10⁻⁹ nm

$\lambda=1282\ nm$

6 0

3 years ago

Sound waves are a- Transverse b- Longitudinal c- Transverse and longitudinal

Katen [24]

Answer:

Sound waves are longitudinal in nature.

Explanation:

There are many types of waves like transverse, longitudinal, electromagnetic wave etc.

Sound waves are longitudinal in nature. In longitudinal type of wave, the medium particles moves parallel to the propagation of the wave. This type of waves move in the form of compression and rarefaction.

In compression, the particle density at a point is very less while in rarefaction, the particle density at a point is very high.

So, the correct option is (b) "longitudinal wave".

3 0

3 years ago

Read 2 more answers