It occurs when energy is supplied or withdrawn :)
To solve this problem it is necessary to apply the rules and concepts related to logarithmic operations.
From the definition of logarithm we know that,

In this way for the given example we have that a logarithm with base 10 expressed in the problem can be represented as,

We can express this also as,

By properties of the logarithms we know that the logarithm of a power of a number is equal to the product between the exponent of the power and the logarithm of the number.
So this can be expressed as

Since the definition of the base logarithm 10 of 10 is equal to 1 then

The value of the given logarithm is equal to 6
Answer:
D
Explanation:
From the information given:
The angular speed for the block 
Disk radius (r) = 0.2 m
The block Initial velocity is:

Change in the block's angular speed is:

However, on the disk, moment of inertIa is:

The time t = 10s
∴
Frictional torques by the wall on the disk is:

Finally, the frictional force is calculated as:

