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mario62 [17]
3 years ago
9

The discovery of the Blombos cave suggests _________________

Physics
2 answers:
anyanavicka [17]3 years ago
5 0
The choices can be found elsewhere and as follows:

<span>a. copper alloy or bronze casting were first used in Sub Saharan Africa.
b. Islam became an economic and religious force in West and North Africa.
c. that abstract thought in humans occurred much earlier than once thought.
d. the French colonies were taken over before the third or fourth centuries.

I think the correct answer is option C. </span>The discovery of the Blombos cave suggests that abstract thought in humans occurred much earlier than once thought. 
Dmitrij [34]3 years ago
5 0

Answer:

that abstract thought in humans occurred much earlier than once thought.

Explanation:

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Trace the path of a ray emitted from the tip of the object toward the focal point of the mirror and then the reflected ray that
Crazy boy [7]

Answer: find the attached files for the answer

Explanation:

The reflected ray appears to have originated from the focal point. We should actually draw a vector from the focal point through the point where the incident ray hits the mirror but we shorten the vector so that its starting point is on the mirror, without changing its angle.

Please find the attached files for the solution

5 0
3 years ago
How many cm3 are there in 1 dm3?
Verdich [7]

The answer is in the picture.

8 0
2 years ago
A stone of mass m = 1.05 kg is released from a height of h = 2.1 m into a pool of water. At a time of t = 1.83 s after hitting t
mote1985 [20]

Answer:

Explanation:

ignoring air resistance, the kinetic energy at water impact will equal the potential energy converted

½mv² = mgh

v = √(2gh)

v = √(2(9.81)2.1) = 6.4188... m/s

after impact, an impulse will result in a change of momentum.

There is a downward impulse due to gravity equal to the weight of the stone and an upward average force due to water resistance and buoyancy force.

FΔt = mΔv

(F - mg)Δt = m(vf - vi)

(F - mg) = m(vf - vi)/Δt

F = m(vf - vi)/Δt + mg

F = m((vf - vi)/Δt + g)

F = 1.05(((½(-6.4188) - -6.4188)/ 1.83) + 9.81)

F = 12.14198...

F = 12.1 N

7 0
2 years ago
Why did boy (the observer) hear the pitch of the sound change? What does this tell us about the frequency of the sound? Support
timofeeve [1]

Answer:

<u>because of the doppler effect</u>

Explanation:

<em>Remember</em>, the doppler effect refers to the changes in sound (frequency of sound) observed by a person who is in a position relative to the wave source.

In this example, we notice as the train comes closer to the boy, the sound becomes louder also increasing the pitch slightly, the doppler effect sets in when the train passes the boy because the boy notices a decrease in the pitch of the moving train.

We learn from the change in the observed sound of the train that the frequency of the sound is determined by the distance of the observer from the wave source.

In other words, the closer the source of the sound to the observer; the faster it travels to the observer, however, the farther it is; the lesser it is; the greater the sound heard.

5 0
3 years ago
A cyclotron designed to accelerate protons has a magnetic field of magnitude 0.15 T over a region of radius 7.4 m. The charge on
klio [65]

Explanation:

It is given that,

Magnetic field, B = 0.15 T

Charge on a proton, q=1.60218\times 10^{-19}\ C

Mass of a proton, m=1.67262 \times 10^{-27}\ kg

The cyclotron frequency is given by :

f=\dfrac{qB}{2\pi m}

f=\dfrac{1.60218\times 10^{-19}\ C\times 0.15\ T}{2\pi \times 1.67262 \times 10^{-27}\ kg}

f = 2286785.40 Hz

or

\omega=14368296.44\ rad/s

\omega=1.43\times 10^7 rad/s

Hence, this is the required solution.

8 0
3 years ago
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