Physical change 1 is the answer
Um student a because they were there a few seconds ahead
Answer:
When an electric field exists in a conductor a current will flow.
This implies a voltage difference between two points on the conductor.
Electrostatics pertains to static charge distributions.
That means that an object such as a charged spherical conductor will be at the same potential (voltage) on both its outer and inner surfaces.
30x30=900
The answer is 900 meters after 30 seconds
I don't like the wording of any of the choices on the list.
SONAR generates a short pulse of sound, like a 'peep' or a 'ping',
focused in one direction. If there's a solid object in that direction,
then some of the sound that hits it gets reflected back, toward the
source. The source listens to hear if any of the sound that it sent
out returns to it. If it hears its own 'ping' come back, it measures
the time it took for the sound to go out and come back. That tells
the SONAR equipment that there IS a solid object in that direction,
and also HOW FAR away it is.
RADAR works exactly the same way, except RADAR uses radio waves.
