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3 years ago

What did the greeks call the mineral they found and why?

1 answer:

6 0

Ancient civilizations had a high demand for raw materials, like clay, diverse rocks and, most of all, metals. These were required for buildings, crafts, agriculture, their armed forces, financial concerns, art and culture. Clays and rocks produced by opencast mining primarily served for the production of bricks and building blocks, which were used for civil and hydraulic engineering.

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A young kid of mass m = 36 kg is swinging on a swing. The length from the top of the swing set to the seat is L = 3.5 m. The boy

lara31 [8.8K]

Answer:

Explanation:

Given

mass of boy=36 kg

length of swing=3.5 m

Let T be the tension in the swing

At top point $mg-T=\frac{mv^2}{r}$

where v=velocity needed to complete circular path

Th-resold velocity is given by $mg-0=\frac{mv^2}{r}$

$v=\sqrt{gr}=\sqrt{9.8\times 3.5}=5.85 m/s$

So apparent weight of boy will be zero at top when it travels with a velocity of $v=\sqrt{gr}$

To get the velocity at bottom conserve energy at Top and bottom

At top $E_T=mg\times 2L+\frac{mv^2}{2}$

Energy at Bottom $E_b=\frac{mv_0^2}{2}$

Comparing two as energy is conserved

$v_0^2=4gl+gl$

$v_0^2=5gL$

$v_0=\sqrt{5gL}=13.09 m/s$

Apparent weight at bottom is given by

$W=\frac{mv_0^2}{L}-mg=\frac{36\times 13.09^2}{3.5}+36\times 9.8=2115.23 N$

6 0

2 years ago

Most of the stars in the Milky Way will end their lives as

umka21 [38]

<span> </span>Most of the stars in the Milky Way will end their lives as white dwarfs

4 0

2 years ago

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Sort the items based on whether they are simple machines or compound machines.

Tom [10]

Answer:

Simple machine: pair of tongs, seesaw and wheelbarrow

Compound machine: sewing machine, fishing rod and reel and crane.

Explanation:

Simple machine is the simplest device to use mechanical advantages. It has simplest mechanism to multiply the magnitude of force.

So, pair of tongs, seesaw and wheelbarrow are the example of simple machine because their mechanism is simplest.

Compound machine is a device that is made up of more than one simple machine.

so, sewing machine, fishing rod and reel and crane are example of compound machine because these devices shows more than one machine in it.

Thus, classification is as follows:

Simple machine: pair of tongs, seesaw and wheelbarrow

Compound machine: sewing machine, fishing rod and reel and crane.

3 0

3 years ago

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If you throw a ball down ward then acceleration immeditely after leaving your hand is

bezimeni [28]

Answer:

9.8m/s²

Explanation:

The acceleration of the ball thrown after leaving my hand is 9.8m/s². This will be the acceleration due to gravity on the body.

Acceleration due to gravity is caused by the pull of the earth on a massive object.
The value of this acceleration is 9.8m/s².
As the ball nears the surface, it comes near zero.

7 0

2 years ago

Choose the answer to fill in the blank, which best completes the sentence.

Allisa [31]

Answer:

A on edge 2020

Explanation:

4 0

2 years ago

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