128.1-127.8= 0.3Hz
<span>129.1-128.1= 1.0Hz </span>
<span>129.1-127.8= 1.3Hz</span>
Answer: 
Explanation:
Centripetal acceleration
is calculated by the following equation:
Where:
is the Earth's orbital speed
is the orbital radius

Air pressure is the weight of air on an area. The weight of air
is due to the gravitational forces between the Earth and the
molecules of its atmosphere.
Answer:

Explanation:
The force on the point charge q exerted by the rod can be found by Coulomb's Law.

Unfortunately, Coulomb's Law is valid for points charges only, and the rod is not a point charge.
In this case, we have to choose an infinitesimal portion on the rod, which is basically a point, and calculate the force exerted by this point, then integrate this small force (dF) over the entire rod.
We will choose an infinitesimal portion from a distance 'x' from the origin, and the length of this portion will be denoted as 'dx'. The charge of this small portion will be 'dq'.
Applying Coulomb's Law:

The direction of the force on 'q' is to the right, since both charges are positive, and they repel each other.
Now, we have to write 'dq' in term of the known quantities.

Now, substitute this into 'dF':

Now we can integrate dF over the rod.

The formula for getting the distance will be distance = speed x time
D = S x T
speed or velocity = 50km/h
time = 0.5 h
the equation will be done directly because it's already in it's SI units
distance = 50km/h x 0.5h
hour cancels hour and the equation remains = 50km x 0.5
Ans = 25 km
the train will move 25 km far in 0.5h