Answer:
Number of electrons are flowing per second is 2.42 x 10¹⁹
Explanation:
The electric current flows through a wire is given by the relation :
....(1)
Here I is current, e is electronic charge, v is drift velocity of electrons and A is the Area of the wire.
But electric current is also define as rate of electrons passing through junction times their charge, i.e. ,
....(2)
Here N is the rate of electrons passing through junction.
From equation (1) and (2).


But area of wire, 
Here d is diameter of wire.
So, 
Substitute 2.91 x 10⁻³ m for d, 0.000191 m/s for v and 6 x 10²⁸ m⁻³ for n in the above equation.

N = 2.42 x 10¹⁹ s⁻¹
Answer:

Given:
Initial velocity (u) = 30 m/s
Final speed (v) = 0 m/s
Acceleration (a) = - 1.5 m/,s²
To Find:
Time in which train will come to rest (t).
Explanation:

So,
Time in which train will come to rest = 20 seconds
An object's momentum is the product of its mass and its velocity:
p = mv
p is its momentum, m is its mass, and v is its velocity.
Given values:
p = -80kg×m/s
m = 8kg
Plug in these values and solve for v:
-80 = 8v
v = -10m/s
Choice D
His. Curbs I b h bs. H b u b