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3 years ago

Name nine elements that have been around so long that we don't even know when they

2 answers:

8 0

What was the first known element? Actually, there were nine elements known to ancient man. They were gold, silver, copper, iron, lead, tin, mercury, sulfur, and carbon.

lora16 [44]3 years ago

7 0

Answer:

gold, silver, copper, iron, lead, tin, mercury, sulfur, and carbon

Explanation:

gold, silver, copper, iron, lead, tin, mercury, sulfur, and carbon

- (These are the most longest elements that have been around very long )

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What does wire gauze help you do

Nookie1986 [14]

Answer:

Explanation:

it helps beakers,flask and other glassware

5 0

3 years ago

Read 2 more answers

7) An apple falls from the tree and the fall is 1.92 seconds. How high up was the apple?

Sergeeva-Olga [200]

Answer:

Ans 171.875 m(according to the units)

Explanation:

As we know,

to find the distance, we need to use this eqn..

speed = distance/ time

So, time is 1.92 s (as given)

the speed is 330 m/s ( in air speed)

so to find it is easy to find by using this

eqn..

speed =distance/time

330 =distance/1.92

330/1.92 =distance

171.875 = distance

6 0

2 years ago

A box slides across a frozen pond toward the left shore as two children standing on opposite shores pull on the box with ropes.

erik [133]

Answer:

given,

children on left shore pulls the rope by 3 N

Children on the right shore pulls the rope by 2 N

speed of the box = 3 m/s

a) Power = Force x Velocity

Power = 3.0 N * 3

Power = 9 Watt

Power = 2.0 N x 3

Power = 6 Watt

b) Net Force = 3.0 N - 2.0 N = 1.0 N

Net Power = 1.0 x 3 Watt

Net Power = 3 Watt

c) net force is acting on the box and at an instant velocity is given so, when the body moves it will accelerate and velocity will change so, the value of part A and B will also change

5 0

3 years ago

An earthquake emits both S-waves and P-waves which travel at different speeds through the Earth. A P-wave travels at 9000 m/s an

Sergio [31]

Answer:

The distance between earthquake center and the measuring station is 1350 kilometers.

Explanation:

Let the earthquake center be at a distance of 'S' meters from the recording station.

Now from the basic relation of distance, speed and time we know that

$Distance=Speed\times Time$

For a Primary wave (P wave) let us assume that it appraoches the measuring station after $t_{1}$ minutes

Thus making use of the above relation we have

$Distance=V_{p}\times Time\\\\\therefore D=9000\times t_{1}.......(i)$

Now since it is given that the secondary wave (S wave) reaches the measuring spot after 2 minutes or 120 seconds thus the time taken by secondary waves to reach recorder equals $t_{1}+120$ making use of the same relation we get

$Distance=V_{s}\times Time\\\\\therefore D=5000\times (t_{1}+120).......(ii)$

Solving equation 'i' and 'ii' we get

$D=5000\times (\frac{D}{9000}+120)\\\\\therefore \frac{D}{5000}=\frac{D}{9000}+120\\\\\frac{D}{5000}-\frac{D}{9000}=120\\\\\therefore D=\frac{120}{\frac{1}{5000}-\frac{1}{9000}}=1350000meters=1350kilomerers$

8 0

3 years ago

A Cassegrain telescope

yuradex [85]

The answer is D.

Hope this helps and have a good day :D

3 0

3 years ago