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2 years ago

Differences between freezing point and melting point (Atleast 5 differences)

Physics

1 answer:

labwork [276]2 years ago

7 0

Answer:

What is freezing point?

A liquid's freezing point is determined at which it turns into a solid. Corresponding to the melting point, the freezing point often rises with increasing pressure. In the case of combinations and for some organic substances, such as lipids, the freezing point is lower than the melting point. The first solid which develops when a combination freezes often differs in composition from the liquid, and the development of the solid alters the composition of the remaining liquid, typically lowering the freezing point gradually. Utilizing successive melting and freezing to gradually separate the components, this approach is used to purify mixtures.

What is melting point?

The temperature at which a purified substance's solid and liquid phases may coexist in equilibrium is referred to as the melting point. A solid's temperature goes up when heat is added to it until the melting point is achieved. The solid will then turn into a liquid with further heating without changing temperature. Additional heat will raise the temperature of the liquid once all of the solid has melted. It is possible to recognize pure compounds and elements by their distinctive melting temperature, which is a characteristic number.

The difference between freezing point and melting point:

While a substance's melting point develops when it transforms from a solid to a liquid, a substance's freezing point happens when a liquid transforms into a solid when the heat from the substance is removed.
When the temperature rises, the melting point can be seen, and when the temperature falls, the freezing point can be seen.
When a solid reaches its melting point, its volume increases; meanwhile, when a liquid reaches its freezing point, its volume decreases.
While a substance's freezing point is not thought of as a distinctive attribute, its melting point is.
While external pressure is a significant component in freezing point, atmospheric pressure is a significant element in melting point.
Heat must be supplied from an outside source in order to reach the melting point for such a state shift. When a material is at its freezing point, heat is needed to remove it from the substance in order to alter its condition.

Reference: Berry, R. Stephen. "When the melting and freezing points are not the same." Scientific American 263.2 (1990): 68-75.

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iVinArrow [24]

Explanation:

D = M/V

We rearrange this equation to get V = M/D

So 14 g/7 g/mL,

the grams cancel out, and we're left with 2 mL.

D is the answer.

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4 years ago

An aircraft flying at a steady velocity of 70 m/s eastwards at a height of 800 m drops a package of supplies.

iren2701 [21]

The motion of the package can be described as the motion of a projectile,

given that it has an horizontal velocity and it is acted on by gravity.

a) $\vec{v}$ = 70·i

b) The package will reach ground in approximately 12.77 seconds.

c) The speed of the package as it lands is approximately 145.51 m/s.

d) The path of the package based on a stationary frame of reference is parabolic

e) The path of the package as seen from the plane is directly vertical downwards

Reasons:

Velocity of the aircraft = 70 m/s

Direction of flight of the aircraft = Eastward

Height from which the aircraft drops the package, h = 800 m

a) The initial velocity of the package, $\vec{v}$ = 70·i

b) The time it will take the package to reach the ground, t, is given by the formula;

$\displaystyle h = \mathbf{\frac{1}{2} \cdot g \cdot t^2}$

Where;

g = The acceleration due to gravity ≈ 9.81 m/s²

Therefore;

$\displaystyle t = \mathbf{\sqrt{ \frac{2 \cdot h}{g} }}$

Which gives;

$\displaystyle t = \sqrt{ \frac{2 \times 800}{9.81} } \approx \mathbf{12.77}$

The time it will take the package to reach the ground, t ≈ 12.77 seconds

c) The vertical velocity just before the package reaches the ground, $v_y$ , is given as follows;

$v_y^2$ = 2·g·h

Therefore;

$v_y$ = √(2·g·h)

Which gives;

$v_y$ = √(2 × 9.81 × 800) ≈ 125.28

$v_y$ ≈ 125.28 m/s

Which gives; $\vec{v}$ = 70·i - 125.28·j

Therefore, |v| = √(70² + (-125.28)²) ≈ 143.51

The speed of the package as it lands, |v| ≈ 143.51 m/s

d) The motion of the package that includes both horizontal and vertical motion is a projectile motion.

Therefore;

The path of the package is the path of a projectile, which is a parabolic shape.

e) As seen by someone on the aeroplane, the horizontal velocity will be

zero, therefore, the package will appear as accelerating directly vertical

downwards.

Learn more about projectile motion here:

brainly.com/question/1130127

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2 years ago

A girl and her bicycle have a total mass of 40 kg. At the top of the hill her speed is 5.0 m/s. The hill is 10 m high and 100 m

Serhud [2]

Answer:

v = 11 m/s is her final speed

Explanation:

work done by gravity = m g Δh = 40×9.8×10 = 3920 Joules

Work done by friction = - force×distance = - 20×100 = - 2000 Joules

[minus sign because friction force is opposite to the direction of motion]

Initial K.E. = (1/2) m u^2 = (1/2) × 40 × 5^2 = 500 Joules

Now, by work energy theorem

Work done = change in kinetic energy.

Final K.E. = initial K.E. + total work = 500 + 3920 - 2000 = 2420 Joules

Now, Final K.E. = (1/2) m v^2 [final speed being v= speed at the bottom]

⇒ 2420 = (1/2)×40×v^2

⇒ 121 = v^ 2

v = 11 m/s is her final speed

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3 years ago

How much work would be needed to lift the ball from the 2-m shelf to the 5-m shelf, and how much potential energy would it have

Stells [14]

Answer:

a) 2.94 N

b) 4.90 N

Explanation:

Let us assume that the weight of the ball is 0.98 N

Solution:

a) An object’s gravitational potential energy depends on two factors which are height and its weight (or mass). The equation for gravitational potential energy (PE) is given as:

Potential energy = weight (w) * height (h)

PE = wh

Potential energy at 2 m shelf = weight * height = 0.98 N * 2 m = 1.96 N

Potential energy at 5 m shelf = weight * height = 0.98 N * 5 m = 4.90 N

The work needed to lift the ball from the 2-m shelf to the 5-m shelf = Potential energy at 5 m shelf - Potential energy at 2 m shelf

The work needed to lift the ball from the 2-m shelf to the 5-m shelf = 4.90 N - 1.96 N = 2.94 N

b) Potential energy at 5 m shelf = weight * height = 0.98 N * 5 m = 4.90 N

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3 years ago

A car travels 30.0 km to the south and then turns around and travels 20.0 km to the north in 1.5 hours time. What is the car's t

mina [271]

Total displacement =10
Average velocity =6.7

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4 years ago

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Differences between freezing point and melting point (Atleast 5 differences)​

Differences between freezing point and melting point (Atleast 5 differences)