I think its b because when there is unbalanced forces it accelerates.
Hope this helps you out
Answer:

Explanation:
For n-=1 state hydrogen energy level is split into three componets in the presence of external magnetic field. The energies are,
,
,

Here, E is the energy in the absence of electric field.
And
are the highest and the lowest energies.
The difference of these energies

is known as Bohr's magneton.
B=2.5 T,
Therefore,

Now,

Therefore, the energy difference between highest and lowest energy levels in presence of magnetic field is 
Answer:
Maximum speed of the car is 17.37 m/s.
Explanation:
Given that,
Radius of the circular track, r = 79 m
The coefficient of friction, 
To find,
The maximum speed of car.
Solution,
Let v is the maximum speed of the car at which it can safely travel. It can be calculated by balancing the centripetal force and the gravitational force acting on it as :


v = 17.37 m/s
So, the maximum speed of the car is 17.37 m/s.
Answer:
= 2.33
Explanation:
.According to snell's law:
n1sin i = n2sin r ,
where n1 is refractive index of the medium in which incident ray is travelling, n2 is the refractive index of the medium in which refracted ray is travelling,
i is angle of incidence,
r is angle of refraction.
Given that,
n1 = 1,
i = 51 degrees,
r = 19.5 degrees. ,
n2= ?
So,
1*sin 51 = n2 sin 19.5
=> n2 = sin51 / sin19.5
= 2.33
Answer:
Explanation:
c slowing down since the distance is going down and the time is moving up.