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Nataly [62]
3 years ago
7

How long have humans been migrating?

Physics
1 answer:
weqwewe [10]3 years ago
8 0

Answer:

about 200k years

Explanation:

because we were migrating as cavemans.

You might be interested in
After Moseley's discovery in 1913, the periodic law stated that physical and chemical properties tend to repeat periodically whe
stich3 [128]

Answer:

Option B

Explanation:

The correct answer is Option B.

Before Moseley's discovery in 1913, In Mendeleev's periodic table the elements rearranged with increasing atomic mass.

Mendeleev was not able to locate hydrogen atom and late isotopes found violate Mendeleev table. The biggest drawback was that the atomic mass was not regular when moving one element to another.

But Moseley's arranged element in the periodic table with increasing atomic number.  

3 0
3 years ago
When you step inside a warm ski lodge on a cold day, you find your glasses fog. why does this occur?
marin [14]
Answer: Condensation of moisture in the air onto the glasses.

Explanation:
When you come from a cold environment into a warm ski lodge, the glasses are at a much lower temperature than that of the lodge.
Because the air in the room contains moisture (water vapor), it condenses on a surface whose temperature is lower than the dew point of the room. 
5 0
4 years ago
How much heat is absorbed by a 450g gold block as energy from the sun causes its temperature to change from 27°C to 32°C? (Speci
kotegsom [21]

Answer:

Q = 1057.5 [cal]

Explanation:

In order to solve this problem, we must use the following equation of thermal energy.

Q=m*C_{p}*(T_{final}-T_{initial})

where:

Q = heat energy [cal]

Cp = specific heat = 0.47 [cal/g*°C]

T_final = final temperature = 32 [°C]

T_initial = initial temperature = 27 [°C]

m = mass of the substance = 450 [g]

Now replacing:

Q=450*0.47*(32-27)\\Q=1057.5[cal]

5 0
3 years ago
b. A string is wrapped around a pulley of radius 0.05 m and moment of inertia 0.2 kg  m2. If the string is pulled with a force
Oduvanchick [21]

Answer:

f = 8 N

Explanation:

Data provided in the question

Radius of the pulley  = r = 0.05 m

Moment of inertia = (I) = 0.2 kg.m^{2}

Angular acceleration = ∝ = 2 rad/sec

Based on the above information

As we know that

Torque is

= force \times  radius

= f \times r

And,

Torque is also

= moment\ of\ inertia \times angular\ acceleration

= I \times \alpha

So,

We can say that

f \times r = I \times \alpha

f \times 0.05 = 0.2 \times 2

0.05f = 0.4

f = 8 N

We simply applied the above formulas

8 0
4 years ago
If HST has a tangential speed of 7,750 m/s, how long is HST’s orbital period? The radius of Earth is 6.38 × 106 m. s
Sladkaya [172]
 the orbital period is 5170 s
6 0
3 years ago
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