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3 years ago

PLZZ HELP Explain how you can tell the difference between a physical and a chemical change.

Physics

1 answer:

Alecsey [184]3 years ago

7 0

Answer:

You can tell the difference between physical and chemical change by looking at the change that takes place like whether it is a permanent or temporary change.

Explanation:

physical change is temporary change and chemical change is permanent change
the original shape of the object can be restored in physical change whereas the original composition of the object will be lost in chemical change
in physical change the change is reversible whereas he chemical change is irreversible and the object takes new shape and position in this change.

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How many lenses with different focal lengths can be obtained by combining two surfaces whose radii of curvature are 4.00 cm and

Dovator [93]

Answer:

The lenses with different focal length are four.

Explanation:

Given that,

Radius of curvature R₁= 4

Radius of curvature R₂ = 8

We know ,

Refractive index of glass = 1.6

When, R₁= 4, R₂ = 8

We need to calculate the focal length of the lens

Using formula of focal length

$\dfrac{1}{f}=(n-1)(\dfrac{1}{R_{1}}+\dfrac{1}{R_{2}})$

Put the value into the formula

$\dfrac{1}{f}=(1.6-1)(\dfrac{1}{4}+\dfrac{1}{8})$

$\dfrac{1}{f}=\dfrac{9}{40}$

$f=4.44\ cm$

When , R₁= -4, R₂ = 8

Put the value into the formula

$\dfrac{1}{f}=(1.6-1)(\dfrac{1}{-4}+\dfrac{1}{8})$

$\dfrac{1}{f}=-\dfrac{3}{40}$

$f=-13.33\ cm$

When , R₁= 4, R₂ = -8

Put the value into the formula

$\dfrac{1}{f}=(1.6-1)(\dfrac{1}{4}-\dfrac{1}{8})$

$\dfrac{1}{f}=\dfrac{3}{40}$

$f=13.33\ cm$

When , R₁= -4, R₂ = -8

Put the value into the formula

$\dfrac{1}{f}=(1.6-1)(\dfrac{1}{-4}-\dfrac{1}{8})$

$\dfrac{1}{f}=-\dfrac{9}{40}$

$f=-4.44\ cm$

Hence, The lenses with different focal length are four.

8 0

2 years ago

An ideal ammeter would have zero resistance while an ideal voltmeter would have infinite resistance, why?.

Dafna1 [17]

Answer: An ideal ammeter would have zero resistance, because to ensure that, there is no voltage drop due to the internal resistance. Similarly, an ideal voltmeter would have infinite resistance, because to ensure that there is no current is drawn by the voltmeter.

Explanation: To find the answer, we need to know about the Ammeter and Voltmeter.

<h3>What is an ammeter?</h3>

An ammeter is a device, that can be used to measure the electric current flows through a circuit in amperes.

An ideal ammeter would have zero resistance, because to ensure that, there is no voltage drop due to the internal resistance when it is connected in series to measure the current.

<h3>What is voltmeter?</h3>

A voltmeter is a device, that can be used to measure the electric potential difference generated between the terminals of an electric circuit in volts.

An ideal voltmeter would have infinite resistance, because to ensure that there is no current is drawn by the voltmeter, when it is connected in parallel to measure the voltage.

Thus, we can conclude that, an ideal ammeter would have zero resistance, because to ensure that, there is no voltage drop due to the internal resistance. Similarly, an ideal voltmeter would have infinite resistance, because to ensure that there is no current is drawn by the voltmeter.

Learn more about the ammeter and voltmeter here:

brainly.com/question/28044897

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6 0

2 years ago

I believe Newton's 1st law is

Bogdan [553]

Answer:

The first law states that if the net force is zero, then the velocity of the object is constant.

5 0

2 years ago

Is it possible for an object to be going 100 miles per hour but have a velocity of zero?

Lesechka [4]

It is possible for on object to be going at 100 miles per hour, but still have a velocity. This is because the object going at 100 miles per hour has speed, which is a scalar quantity, which is defined by only magnitude, but the velocity of the object can be 0, since velocity is a vector quantity which is defined by both magnitude and direction.

Since this object only has magnitude and no direction (which is not given), then the velocity can be 0

5 0

3 years ago

According to Dr. Ridel's Levels of Critical Thinking in Chapter 1, what level of critical thinking applies to your current statu

Karolina [17]

The levels of critical thinking classify people into six categories depending on their ability to reflect.

<h3>What is critical thinking?</h3>

This refers to the ability to analyze information, situations, etc. as well as apply, synthesize or evaluate the information learned.

<h3>What are the levels?</h3>

According to Dr. Ridel, the levels are:

Unreflective thinking: They do not reflect on information and lack the skills to have critical thinking.
Challenged thinker: This person knows critical thinking is important but has difficulties to have critical thinking.
Practicing thinker: This person has better-thinking abilities.
Advanced thinker: This person can critically think and has the skills to improve this process.
Master thinker: This person is in control of this process and shows superior thinking abilities.

Learn more about critical thinking in: brainly.com/question/12980631

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4 0

2 years ago