Answer:
Unknown
Explanation:
By definition, we can't observe what's inside there, because no light – no information of any kind – can escape a black hole. But astrophysical theories suggest that, at the core of a black hole, all the black hole's mass is concentrated into a tiny point of infinite density. This point is known as a singularity.
Answer:

Explanation:
The momentum change is defined as:

Taking the downward motion as negative and the upward motion as positive, we have:

Replacing (2) and (3) in (1):

Answer:Shifted towards Left by distance of 2.243 m
Explanation:
Given
Mass of john 
Mass of barbara 
John is standing at 
Barbara is standing at 




Now if they change their Position then



Thus we can see that center of mass shifted towards left by a distance of
because heavier is shifted towards left
Answer:
She can consider using agricultural waste or dried dung.
Explanation:
No doubt, biomass has become a crucial source of energy to the society, with almost 90% of the households in rural area now relying on biomass for energy. Biomass has become a great option for household heating and cooking. It is locally available and abundant. It is a clean type of fuel, unlike fossil fuels and it somehow helps in cleaning our environment as it traps carbondioxide. Some common types of biomass include dried dung, agricultural waste, or even charcoal.