A cavity that has a hole in it......it's the best example of black body radiators....
Answer:

Explanation:
<u>The total momentum of a system is defined by:</u>

Where,
is the total momentum or it could be expressed also as
.
and
represents the masses of the objects interacting in the system.
and
are the velocities of the objects of the system.
<em>Remember: </em><em>The momentum is a fundamental physical magnitude of vector type.</em>
We have:


We are going to take the east side as positive, and the west side as negative. Then the velocity of the car B, has to be <u>negative</u>. It goes in a different direction from car A.

Then the total momentum of the system is:

I believe the answer is energy
<span>He should study the chapter about laws to get a better understanding about the laws that govern physical objects</span>
Answer:
I = 16amp
Explanation:
Charge coulomb ( Q ) = It
Where I =current in ampere
t = time = 5 seconds
80 = I × 5
I = 80/5
I = 16amp
The current through the circuit will be I = 16amp