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3 years ago

Which would show an example of how physical changes are reversible?

Physics

2 answers:

kondor19780726 [428]3 years ago

8 0

Answer:

Melting tin and then cooling it into a mold

Explanation:

When you melt something, and when it cools it returns to its physical state, therefore the physical changes are reversible. For example, take chocolate. When chocolate melts its liquid, then when it's in a colder situation it becomes solid again and so on, the changes are reversible.

il63 [147K]3 years ago

8 0

Answer:

Explanation:

the physical change was the gold bar being cut and if it is put back together the physical change is reversed

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There is up to 30 times more gold in a tons of old mobile phones than in a tons of gold ore. true or false

FrozenT [24]

Answer:

true

Explanation:

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2 years ago

Aunt Matilda goes to a well and throws a penny straight down the well at 3.0 m/s. She hears a splash after 0.5 seconds. How deep

nevsk [136]

Answer : The correct option is (d) 2.73 m

Explanation :

By the 2nd equation of motion,

$s=ut+\frac{1}{2}at^2$

where,

s = distance or height = ?

u = initial velocity = 3.0 m/s

t = time = 0.5 s

a = acceleration due to gravity = $9.8m/s^2$

Now put all the given values in the above equation, we get:

$s=(3.0m/s)\times (0.5s)+\frac{1}{2}\times (9.8m/s^2)\times (0.5s)^2$

$s=2.73m$

Therefore, the correct option is (d) 2.73 m

8 0

3 years ago

(b) Can the speed of a rocket exceed the exhaust speed of the fuel? Explain.

muminat

<u>Yes. The speed of a rocket can exceed the exhaust speed of the fuel.</u>

How this is explained?

The thrust of the rocket does not depend on the relative speed of the gases or the relative speed of the rocket.
It depends on conservation of momentum.

What is conservation of momentum?

Conservation of momentum, general law of physics according to which the quantity called momentum that characterizes motion never changes in an isolated collection of objects; that is, the total momentum of a system remains constant.

Momentum is equal to the mass of an object multiplied by its velocity and is equivalent to the force required to bring the object to a stop in a unit length of time.
For any array of several objects, the total momentum is the sum of the individual momenta.
There is a peculiarity, however, in that momentum is a vector, involving both the direction and the magnitude of motion, so that the momenta of objects going in opposite directions can cancel to yield an overall sum of zero.

To know more about conservation of momentum, refer:

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1 year ago

A wildebeest runs with an average speed of 4.0\,\dfrac{\text m}{\text s}4.0 s m 4, point, 0, start fraction, start text, m, en

devlian [24]

Answer:

60m

Explanation:

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3 years ago

Which type of reaction does this diagram represent?

Sever21 [200]

Nuclear fusion because atomic nuclei combine to form a heavier nucleus. Option A is correct.

<h3>What is nuclear fusion?</h3>

The process by which two or more tiny nuclei unite to generate a bigger nucleus is known as a nuclear fusion reaction.

The more energy it takes to liberate an electron from a smaller atom. This is referred to as binding energy.

As a result, when two little nuclei fuse together, there is more binding energy than when two big nuclei fuse together.

For example, the fusion of two hydrogen atoms produces more energy than the fusion of one helium atom, and surplus energy is expelled into space upon binding.

Nuclear fusion because atomic nuclei combine to form a heavier nucleus.

Hence, option A is correct.

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2 years ago