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3 years ago

Which of these is an example of physical change?

2 answers:

8 0

That will be A melting a substance that's because the rest are examples of chemical changes and also its the same thing but in a different form.

aleksandrvk [35]3 years ago

7 0

Answer:

Melting a substance

Explanation:

Melting a substance is a physical change. It is a physical change because the process is irreversible that is the product after the substance is melted can be converted back to its original state.

Taking ice as an example, ice being a solid matter can be melted by applying heat. This melted ice will change to water. The water which is the product formed can be freezed to change it back to its initial state which is ice. Hence melting is a physical change.

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A swimming pool is 50 ft wide and 100 ft long and its bottom is an inclined plane, the shallow end having a depth of 4 ft and th

Nina [5.8K]

Explanation:

We define force as the product of mass and acceleration.

F = ma

It means that the object has zero net force when it is in rest state or it when it has no acceleration. However in the case of liquids. just like the above mentioned case, the water is at rest but it is still exerting a pressure on the walls of the swimming pool. That pressure exerted by the liquids in their rest state is known as hydro static force.

Given Data:

Width of the pool = w = 50 ft

length of the pool = l= 100 ft

Depth of the shallow end = h(s) = 4 ft

Depth of the deep end = h(d) = 10 ft.

weight density = ρg = 62.5 lb/ft

Solution:

a) Force on a shallow end:

$F = \frac{pgwh}{2} (2x_{1}+h)$

$F = \frac{(62.5)(50)(4)}{2}(2(0)+4)$

$F = 25000 lb$

b) Force on deep end:

$F = \frac{pgwh}{2} (2x_{1}+h)$

$F = \frac{(62.5)(50)(10)}{2} (2(0)+10)$

$F = 187500 lb$

c) Force on one of the sides:

As it is mentioned in the question that the bottom of the swimming pool is an inclined plane so sum of the forces on the rectangular part and triangular part will give us the force on one of the sides of the pool.

1) Force on the Rectangular part:

$F = \frac{pg(l.h)}{2}(2(x_{1} )+ h)$

$x_{1} = 0\\h_{s} = 4ft$

$F = \frac{(62.5)(100)(2)}{2}(2(0)+4)$

$F =25000lb$

2) Force on the triangular part:

$F = \frac{pg(l.h)}{6} (3x_{1} +2h)$

here

h = h(d) - h(s)

h = 10-4

h = 6ft

$x_{1} = 4ft\\$

$F = \frac{62.5 (100)(6)}{6} (3(4)+2(6))$

$F = 150000 lb$

now add both of these forces,

F = 25000lb + 150000lb

F = 175000lb

d) Force on the bottom:

$F = \frac{pgw\sqrt{l^{2} + ((h_{d}) - h(s)) } (h_{d}+h_{s}) }{2}$

$F = \frac{62.5(50)\sqrt{100^{2}(10-4) } (10+4) }{2}$

$F = 2187937.5 lb$

7 0

3 years ago

On a particle level, what happens when thermal conduction occurs within a solid?

yKpoI14uk [10]

Answer:

Faster particles bump into slower particles ( A )

Explanation:

Thermal conduction in a solid involves the microscopic collision of particles in the solid and this particles are made up of electrons, molecules and atoms. the collisions occur when faster particles collide with slower particles and this happens in a disorganized manner.

when cannot say for sure in what direction each of the particles is moving but there is surely collisions between particles which in turn results to transfer of kinetic and potential energies

7 0

3 years ago