because water is loosely packed but when it is cold it becomes closely packed in order to form ice and thus the force attraction between them also increase.
Answer:
5 ohms
Explanation:
Given:
EMF of the ideal battery (E) = 60 V
Voltage across the terminals of the battery (V) = 40 V
Current across the terminals (I) = 4 A
Let the internal resistance be 'r'.
Now, we know that, the voltage drop in the battery is given as:
Therefore, the voltage across the terminals of the battery is given as:

Now, rewriting in terms of 'r', we get:

Plug in the given values and solve for 'r'. This gives,

Therefore, the internal resistance of the battery is 5 ohms.
Answer
Nature of the surfaces.
Explanation
Friction is the the force that opposes motion between two surfaces that are in relative motion. If two objects are in contact, one of it or both must be in motion for friction to exist.
Friction is affected by a number of factors.
One is the weight of the object. The more the weight of the object the higher the friction between it and the surface.
The other factor is the nature of the surfaces. Rough surfaces contribute to high friction while smooth surfaces reduces the friction between surfaces.
It's usually taken from <span>400 to 700 nm.</span>