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3 years ago

14

Based on The MOHS hardness Scale, which mineral could be scratched by a penny but not by a fingernail

1 answer:

melomori [17]3 years ago

6 0

The correct answer is B. Calcite

Explanation:

Mohs hardness scale indicates the hardness of minerals using a scale from 1 to 10 as well as defining the objects or tools that can be used to scratch the minerals. These two features of minerals are shown in the table of the image. About this, it is shown gypsum and talc can be scratched by just a fingernail, considering minerals with a hardness of 2.5 or below can be scratched by a fingernail. In the case of calcite that has a hardness of 3, this cannot be scratched by a fingernail, but it can be scratched by a penny, which works for minerals with a hardness of 3.5 or below. Thus, the correct answer is Calcite.

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Two cars collide at an icy intersection and stick together afterward. The first car has a mass of 1200 kg and was approaching at

igomit [66]

To resolve point A and B we need the concepts related to conservation of momentum (By collision) and Kinetic Energy. Conservation of momentum is given by the equation,

$m_1\vec{v_1}+m_2\vec{v_2} = (m_1+m_2)\vec{v}$

Our values in the statment are:

$m_1 = 1200kg$

$v_1 = 6m/s$

$m_2 = 900kg$

$v_2 = 24m/s$

Part A) As it is in an icy intersection, there is two different components (x,y) then,

$1200(-6\hat{j})+900(-24\hat{i}) = (1200+900)\vec{v}$

$2100\vec{v} = -21600\hat{i}-7200\hat{j}$

$\vec{v} = -72/7\hat{i}-24/7\hat{j}$

Then the magnitude is,

$|\vec{v}| = 9.6525m/s$

Part B) To obtain the Kinetic Energy Loss we need to use its equation, which is given by,

$KE_i = \frac{1}{2}m_1v_1^2+\frac{1}{2}m_2v_2^2$

$KE_i = \frac{1}{2}(1200)(6)^2+\frac{1}{2}(900)(24)^2$

$KE_i = 280.8kJ$

The final energy is given by,

$KE_f = \frac{1}{2}(m_1+m_2)v_f^2$

$KE_f = \frac{1}{2} (1200+900)(9.65)$

$KE_f =97778.625J$

Then the change in Kinetic Energy is

$\Delta KE = KE_f-KE_i = 97.778kJ- 280.8kJ$

$\Delta KE = -183.02kJ$

<em>There was a loss of KE of 183.02kJ</em>

5 0

3 years ago

A ball is rolled at a velocity of 25 m/sec. after 13.5 seconds, it comes to a stop . What is the acceleration of the ball?

nexus9112 [7]

Answer:

The answer to your question is a = -1.85 m/s² the acceleration is negative because it is coming to stop.

Explanation:

Data

vo = 25 m/s

t = 13.5 s

a= ?

vf = 0 m/s

Formula

vf = vo + at

solve for a

a = (vf - vo)/t

Substitution

a = (0 - 25) / 13.5

Simplification

a = -25/13.5

Result

a = -1.85 m/s²

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3 years ago

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Vanyuwa [196]

Answer:

2H20 --> 2H2 + 02

Explanation:

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Thepotemich [5.8K]

True. Fun fact. Hope this helps

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Zarrin [17]

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Explanation:

Acceleration is speeding up, the ball is slowing down making it negative acceleration

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