This problem uses the relationships among current
I, current density
J, and drift speed
vd. We are given the total of electrons that pass through the wire in
t = 3s and the area
A, so we use the following equation to to find
vd, from
J and the known electron density
n,
so:

<span>The current
I is any motion of charge from one region to another, so this is given by:
</span>

The magnitude of the current density is:

Being:

<span>
Finally, for the drift velocity magnitude vd, we find:
</span>
Notice: The current I is very high for this wire. The given values of the variables are a little bit odd
Use the impulse-momentum theorem.

Substitute your known values:

Hope this helps!
Answer:

Explanation:
To solve this exercise it is necessary to take into account the concepts related to gravitational potential energy, as well as the concept of perigee and apogee of a celestial body.
By conservation of energy we know that,

Where,

Replacing


Our values are given by,





Replacing at the equation,


Therefore the Energy necessary for Sputnik I as it moved from apogee to perigee was 
Answer:
The car exerts a force on the truck which is c.) 6000 N.
Explanation:
If the truck exerts a force of 6000 N on the car then according to Newton's Third Law of Motion that every action has an equal and opposite reaction we can say that the force exerted by the car on the truck is 6000 N.
The only reason the truck is able to move the car is because of the frictional forces. That is frictional force of the trucks tires on the surface of the road and the frictional forces of the cars tire on the surface of the road, and since these forces are not equal this therefore gives rise to motion.