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3 years ago

Which of the following is a chemical change?

Physics

2 answers:

e-lub [12.9K]3 years ago

4 0

A screw driver rusting when left in a pail of water is a chemical reaction

Kisachek [45]3 years ago

4 0

Answer:

a screwdriver rusting when left in a pail of water

Explanation:

In case of chemical change we can say that there must be a chemical reaction due to which there will be a change in the chemical reactants.

As we can see the given options

1). wind breaking down a rock into smaller pieces

There is no chemical reaction between them and it just a physical change of big size to smaller size

2). a leaf falling off of a tree during a storm

As we know that here also leaf detach from the tree so there is only physical change again.

3). a screwdriver rusting when left in a pail of water

Here we will have a chemical change due to which iron made its oxide due to chemical reaction of iron and oxygen

4). a block of ice melting in the sun

This is also physical change in which water molecules change from its solid state to liquid state

So here correct answer will be

a screwdriver rusting when left iwind breaking down a rock into smaller pieces

a leaf falling off of a tree during a storm

a screwdriver rusting when left in a pail of water

a block of ice melting in the sunwind breaking down a rock into smaller pieces

a leaf falling off of a tree during a storm

a screwdriver rusting when left in a pail of water

a block of ice melting in the sunwind breaking down a rock into smaller pieces

a leaf falling off of a tree during a storm

a screwdriver rusting when left in a pail of water

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3 years ago

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A car covers 120 km in 3 hours calculate its speed in m/s

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Answer:

11.1 m/s

Explanation:

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2 years ago

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A mass is tied to a string and swung in a horizontal circle with a constant angular speed. show answer No Attempt If this speed

Liono4ka [1.6K]

Answer:

The tension in the string is quadrupled i.e. increased by a factor of 4.

Explanation:

The tension in the string is the centripetal force. This force is given by

$F = \dfrac{mv^2}{r}$

m is the mass, v is the velocity and r is the radius.

It follows that $F \propto v^2$ , provided m and r are constant.

When v is doubled, the new force, $F_1$ , is

$F_1 = \dfrac{m(2v)^2}{r} = \dfrac{4mv^2}{r} = 4\dfrac{mv^2}{r} = 4F$

Hence, the tension in the string is quadrupled.

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3 years ago

Which direction will the box move?

Yuki888 [10]

Net force

F1-F2-F3
5-10-20
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As it's negative the box will move left

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2 years ago

A wave is 8 meters long and has a frequency of 3 Hz. Find speed

Olenka [21]

Answer:

The speed is 24 $\frac{meter}{s}$

Explanation:

A wave is a disturbance that propagates through a certain medium or in a vacuum, with transport of energy but without transport of matter.

The wavelength is the minimum distance between two successive points of the wave that are in the same state of vibration. It is expressed in units of length (m).

Frequency is the number of vibrations that occur in a unit of time. Its unit is s⁻¹ or hertz (Hz).

The speed of propagation is the speed with which the wave propagates in the middle, that is, the magnitude that measures the speed at which the wave disturbance propagates along its displacement. Relate wavelength (λ) and frequency (f) inversely proportionally using the following equation:

v = f * λ.

In this case, λ= 8 meter and f= 3 Hz

Then:

v= 3 Hz* 8 meter

So:

v= 24 $\frac{meter}{s}$

The speed is 24 $\frac{meter}{s}$

5 0

3 years ago