Because metric units use the deca system, 1km = 1000m = 100 000cm etc...
Every unit of density is
(a unit of mass) divided by (a unit of volume) .
The one most widely used is [ gram/cubic centimeter ] , but there's no reason that you MUST use this same unit every time you talk about density. You can use (any unit of mass) divided by (any unit of volume) that you want ... the best choices are always the ones that end up with the most convenient number.
Whatever units of mass and volume you decide to use, it's easy for anybody to convert it to [ gram/cubic centimeter ] if they want to.
Answer:
Explanation:
Given
Initial angular velocity 
Initial speed 
Coefficient of kinetic friction 
As No external torque is applied therefore angular momentum is conserved
For rolling without slipping 
acceleration provided by surface
Speed of ball after 
using 
v=final velocity
u=initial velocity
thus 
We know, Power = Voltage * Current
P = 660 * 12 = 7920 watt
In short, Your Answer would be Option A
Hope this helps!
