To solve this problem we will use the linear motion description kinematic equations. We will proceed to analyze the general case by which the analysis is taken for the second car and the tenth. So we have to:

Where,
x= Displacement
= Initial velocity
a = Acceleration
t = time
Since there is no initial velocity, the same equation can be transformed in terms of length and time as:

For the second cart

When the tenth car is aligned the length will be 9 times the initial therefore:

When the tenth car has passed the length will be 10 times the initial therefore:

The difference in time taken from the second car to pass it is 5 seconds, therefore:

From the first equation replacing it in the second one we will have that the relationship of the two times is equivalent to:


From the relationship when the car has passed and the time difference we will have to:



Replacing the value found in the equation given for the second car equation we have to:

Finally we will have the time when the cars are aligned is


The time when you have passed it would be:


The difference between the two times would be:

Therefore the correct answer is C.
Radiation is the only transfer in a vacuum
Answer:
A moving electric charge creates a magnetic field at all points in the surrounding region.
An electric current in a conductor creates a magnetic field at all points in the surrounding region.
A permanent magnet creates a magnetic field at all points in the surrounding region.
Explanation:
Magnetic field can be produced by:
- moving charges (i.e. a moving electron, or a current in a conductor)
- A magnet
The strength of the magnetic field produced by a current-carrying wire is

where
I is the current
r is the distance from the wire
As we see from the formula, the magnetic field is produced at all points in the surrounding region, because B becomes zero only when r becomes infinite. The same is true for the magnetic field created by a single moving charge or by a magnet.
The following choices instead are not correct:
- A single stationary electric charge creates a magnetic field at all points in the surrounding region.
- A distribution of electric charges at rest creates a magnetic field at all points in the surrounding region.
Because they involve the presence of stationary charges, and stationary charges do not produce magnetic fields.
Answer:
Q = 1.35*10⁻¹¹ C.
Explanation:
By definition, the capacitance of a capacitor, is the charge on one of the plates, divided by the potential difference between them, as follows:

At the same time, we can show (applying Gauss' Law to the surface of one of the plates), that the capacitance of a parallel-plate capacitor (with a dielectric of air), can be written as follows:
C = ε₀*A / d
Replacing by the values of A, and d, and taking into account that
ε₀ = 8.85*10⁻¹² F/m,
we get the value of the capacitance as follows:
C = 8.97*10⁻¹² F
As the voltage of an AA battery is 1.5 V, and is all applied to the capacitor, we can conclude that the charge on one of the plates is as follows:
Q = C* V = 8.97*10⁻¹² F* 1.5 V = 1.35*10⁻¹¹ C