The answer would be:
C. An unbalanced force has acted on the vehicle.
The presence of an unbalanced force will accelerate an object, the second law of motion dictates this (Although not explicitly). Lets knock out the rest of the choices.
If a balance force acted on the vehicle, then the vehicle would be at rest. The mass of the vehicle did not change (Unless it falls apart, which I doubt). The direction of the vehicle does not change and it will only do so if another force and a stronger one at that will counteract the current net force acting on the vehicle.
Hope you got your answer here, although you did not ask for an explanation, maybe this will help you figure some of the other questions you have on your own.
All the 4 processes are correct answer to change the state of matter. Hope it helps.
Apparently, the question is looking for A. electric potential energy;
but I don't think that's quite right. Electric potential difference is expressed in Joules / Coulomb which is the work to move a charge between 2 points
Example: If the electric field between, say, between 2 capacitor plates is
E = 100 Newtons / Coulomb then the work done in moving a unit of charge from the negative plate to the positive plate separted by 1 cm is
V = E * d = 100 Newtons / Coulomb * .01 meters = 1 Newton-meter / Coulomb
= 1 Joule / Coulomb which is the electric potential or potential difference
(The definition of electric potential between points is "the work moving a unit positive test charge from one point to the other")
Now in our above example where V = 1 Joule / Coulomb
if we move 10 Coulombs from the negative plate to the positive plate
W = V Q = 1 Joule / Coulomb * 10 Coulombs = 10 Joules
where work done has the correct units of Joules.
Your textbook should help clarify this.
Mechanical waves need material stuff to travel through.
They cannot travel through vacuum.
That's why we can't hear the explosions on the sun.
That's also why astronauts standing on the moon or working outside the Space Station have to use radio to talk to each other, even if they're only a few inches apart. There's no air between them, or any other material stuff. So sound can't travel between them.
