Answer:
Black Hole
Explanation:
A black hole is a very dense and massive stellar object, which has a field of gravity so large that not even light can escape it.
Since it does not emit light, <u>we cannot see them directly</u>, hence the name of black hole.
So in this case,<u> if the object has a mass of 8 solar masses that is enough to form a black hole</u>, and <u>also cannot be seen</u>, all of this indicates that the object we are talking about is a black hole.
It should be mentioned that although these objects do not emit light, because it cannot escape due to the immense force of gravity, black holes can be detected by a type of radiation emitted on their event horizon due to quantum effects called Hawking radiation .
Explanation:
average speed = total distance travelled / total time travelled
time to travel the first 6km: 6 / 50 = 3/25 (h)
time to travel the next 6km: 6 / 90 = 1/15 (h)
[I think there's problem in the question 'cause 900km/h sounds impossible for normal person to travel in normal condition]
The total time: 3/25 + 1/15 = 14/75 (h)
Average speed over the 12 km drive will be:

Answer:
The magnitude of magnetic field at given point =
×
T
Explanation:
Given :
Current passing through both wires = 5.0 A
Separation between both wires = 8.0 cm
We have to find magnetic field at a point which is 5 cm from any of wires.
From biot savert law,
We know the magnetic field due to long parallel wires.
⇒ 
Where
magnetic field due to long wires,
,
perpendicular distance from wire to given point
From any one wire
5 cm,
3 cm
so we write,
∴ 

![B =\frac{ 4\pi \times10^{-7} \times5}{2\pi } [\frac{1}{0.03} + \frac{1}{0.05} ]](https://tex.z-dn.net/?f=B%20%3D%5Cfrac%7B%204%5Cpi%20%5Ctimes10%5E%7B-7%7D%20%5Ctimes5%7D%7B2%5Cpi%20%7D%20%5B%5Cfrac%7B1%7D%7B0.03%7D%20%2B%20%5Cfrac%7B1%7D%7B0.05%7D%20%5D)

Therefore, the magnitude of magnetic field at given point = 
Answer:
Time elapsed
Explanation:
Acceleration is a vector quantity. It is defined as:

where
v is the final velocity
u is the initial velocity
t is the time elapsed
Acceleration is measured in meters per second squared (m/s^2). It must be noticed that acceleration is a vector, so it also has a direction. In particular:
- when acceleration is negative, it means that the object is slowing down, so acceleration is in opposite direction to the velocity
- when acceleration is positive, it means that the object is speeding up, so acceleration is in the same direction as the velocity