Answer:
c)by a factor of four
Explanation:
The total energy of a simple harmonic oscillator is given by

where
k is the spring constant of the oscillator
A is the amplitude of the motion
In this problem, the amplitude of the oscillator is doubled, so
A' = 2A
Therefore, the new total energy is

So, the total energy increases by a factor 4.
Density = Mass/Volume
So, given mass = 20 g and volume = 40 cm^3
By substituting in above equation, Density = 20/40 = 0.5 g/cm^3
Hope it helps.
Answer:Due to change in direction
Explanation:
Given
Initially train has traveled a 100 km in North and after exchanging some railroad cars, it traveled 100 in south.
The velocity of the train changes as it direction of motion changes. Velocity is the vector quantity which require direction and magnitude for its reperesentation.