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3 years ago

15

Which statement defines an ore? Rock broken down to become part of the topsoil. Rock dug out from the earth to use in constructi

on. Rock dug out from the deep inside earth and refined. Rock exposed as a result of loss of topsoil.

2 answers:

Anika [276]3 years ago

5 0

Rock dug out from the deep inside earth and refined.

Explanation:

Ores are usually rocks dug out from deep within the earth and refined.

An ore is an aggregate of metalliferous minerals with gangue that can be won at profit under current economic conditions.

Ores are rocks and rocks can be ores if they contain viable economic minerals.

They are usually naturally formed and they contain different minerals.

For example cassiterite is a known ore of tin.

Learn more:

Rocks brainly.com/question/2817889

#learnwithBrainly

Ivanshal [37]3 years ago

5 0

Answer:

C.

Explanation:

According to E2020, the correct answer to this problem is C. Rock dug out from the deep inside earth and refined.

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57.0- g tennis ball is traveling straight at a player at 21.0 m/ s. The player volleys the ball straight back at 25.0 m/ s. If t

Yakvenalex [24]

Answer:43.7 N

Explanation:

Given

Mass of tennis ball is =57 gm

velocity of ball=21 m/s

The player volleys the ball straight back at 25 m/s(i.e. in opposite of initial direction)

time of contact=0.06 s

We know change in momentum $(\Delta P) =Impulse(Fdt)$

initial momentum $=57\times 10^{-3}\times 21$

final momentum $=-57\times 10^{-3}\times 25$

change in momentum

$\Delta P=57\times 10^{-3}\times 21-(-57\times 10^{-3}\times 25)$

$\Delta P=57\times 10^{-3}\times 46=2.622 kg-m/s$

Now 2.622 $=F_{avg}\times 0.06$

$F_{avg}=43.7 N$

4 0

3 years ago

What are the three types of motion

Cloud [144]

Rectilinear Motion, Circular Motion and Periodic Motion.

7 0

3 years ago

A 82-kg skydiver has a speed of 40 m/s at an altitude of 490 m above the ground. Calculate the total mechanical energy of the sk

Sav [38]

Answer:

$ME=459,364J$

Explanation:

Mechanical Energy=Potential Energy+ kinetic Energy

$m=82kg,g=9.8N/kg,h=490m,v=40m/s$

To calculate Kinetic Energy:-

$KE=\frac{1}[2}mv^2\\=\frac{1}{2}\times82kg \times(40m/s)^2\\=65600J$

To calculate Potential Energy:-

$PE=mgh\\=82kg \times9.8N/kg \times490\\=393764$

therefore,

$ME=KE+PE\\=65600+393764\\=459364J$

The skydiver's total mechanical energy is 459365J

8 0

3 years ago

A fire truck emits an 880Hz siren. As the truck approaches an observer on the sidewalk, he perceives the pitch to be 950Hz. Appr

Ludmilka [50]

Answer:

The pitch that he hears after the truck passes and is moving away is 819.6 Hz.

Explanation:

The pitch that he hears after the truck passes and is moving away can be calculated using the following equation:

$f = f_{0}*\frac{v_{s} \pm v_{o}}{v_{s} \pm v_{f}}$

Where:

$f$ : is the perceived frequency

$f_{0}$ : is the emitted frequency

$v_{s}$ : is the speed of sound = 340 m/s

$v_{o}$ : is the speed of the observer = 0 (he is not moving)

$v_{f}$ : is the speed of the fire truck

First, we need to find the speed of the fire truck. When it approaches the observer we have:

$f = f_{0}*\frac{v_{s} + v_{o}}{v_{s} - v_{f}}$

$950 Hz = 880 Hz*\frac{340 m/s}{340 m/s - v_{f}}$

$v_{f} = 340 m/s - \frac{880 Hz*340 m/s}{950 Hz}$

$v_{f} = 25.05 m/s$

Hence, the speed of the fire truck is 25.05 m/s.

Now, we can calculate the pitch that the observer hears after the truck passes:

$f = f_{0}*\frac{v_{s} - v_{o}}{v_{s} + v_{f}}$

$f = 880 Hz*\frac{340 m/s}{340 m/s + 25.05 m/s}$

$f = 819.6 Hz$

Therefore, the pitch that he hears after the truck passes and is moving away is 819.6 Hz.

I hope it helps you!

7 0

3 years ago

An airplane flies northwest for 250 mi and then west for 150 mi. What is the resultant displacement of the plane after this time

Kazeer [188]

Answer:371.564 mi

Explanation:

Given

Airplane flies northwest for 250 mi and then travels west 150 mi

That is first it travels 250cos45 in - ve x direction and simultaneously 250sin45 in y direction

after that it travels 150 mi in -ve x direction

So its position vector is given by

$r=-250cos45\hat{i}-150\hat{i}+250sin45\hat{j}$

$r=-\left ( 250cos45+150\right )\hat{i}+250sin45\hat{j}$

so magnitude of displacement is

$|r|=\sqrt{\left ( \frac{250}{\sqrt{2}}+150\right )^2+\left ( \frac{250}{\sqrt{2}}\right )^2}$

|r|=371.564 mi

7 0

3 years ago