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.
<em>Reference: Berry, R. Stephen. "When the melting and freezing points are not the same." Scientific American 263.2 (1990): 68-75.</em>
Answer:
Momentum after collision will be 6000 kgm/sec
Explanation:
We have given mass of the whale = 1000
Initial velocity v = 6 m/sec
It collides with other mass of 200 kg which is at stationary
Initial momentum of the whale = 1000×6 = 6000 kgm/sec
We have to find the momentum after collision
From conservation of momentum
Initial momentum = final momentum
So final momentum = 6000 kgm/sec
Answer:
D. Both occur between objects independently whether they are in contact or not.
Explanation:
- The gravitational force is a force that is exerted between two (or more) objects having mass. This force is always attractive and its magnitude is given by
where G is the gravitational constant, m1 and m2 are the two masses, and r is the distance between the two masses.
- The electrical force is a force that is exerted between two (or more) objects having electrical charge. It can be either attractive or repulsive, depending on the sign of the two charges, and its magnitude is given by
where k is the Coulomb's constant, q1 and q2 are the two charges, and r the distance between the two charges.
Looking at both formulas, we see that the two forces are present even when the two objects are not in contact with each other (in fact, r can assume any value in the formula). They are said to be non-contact forces. Therefore, the correct option is
D. Both occur between objects independently whether they are in contact or not.
