It is a field of study that make direct use of phenomena that is "quantum-mechanincal", such as superposition and entanglement. It's used to perform operations on data
Answer:
A.The positive z-direction
Explanation:
We are given that
Linear charge density of long line which is located on the x-axis=
Linear charge density of another long line which is located on the y-axis=
We have to find the direction of electric field at z=a on the positive z-axis if and are positive.
The direction of electric field at z=a on the positive z-axis is positive z-direction .
Because and are positive and the electric field is applied away from the positive charge.
Hence, option A is true.
A.The positive z-direction
Explanation:
Mass of bumper cars, 
Initial speed of car A, 
Initial speed of car Z, 
Final speed of car A after the collision, 
We need to find the velocity of car Z after the collision. Let it is equal to 
. Using the conservation of momentum as :
So, the velocity of car Z after the collision is (-12 m/s). Hence, this is the required solution.
If you are asking for a proof on having at least 3 dimensions in space, you can find the physical proof anywhere in your daily life activities. Just the fact that solids have volumes is a proof already that we live in a three-dimensional space. We can move forwards, backwards, sidewards and in all other directions possible.
When you go right into detail, the fundamental laws governing these proofs are very technical. They have differential equations to show as proof. It is too detailed to discuss here. The important things is that, these fundamental laws are what explains the science in our basic activities and natural phenomena:
*Gravitation and planetary motion
* Translation, rotation, magnetic field, forces
* Integrals of equations:
