The part you talk into, that converts the sound of your voice
into an electrical signal, is a tiny microphone.
-- The sound waves from your voice are ripples in the air.
-- In most microphones, there's a tiny coil of wire hanging
between the ends of a tiny magnet.
-- When the ripples in the air hit the little coil of wire, they
make it vibrate (wiggle) slightly.
-- When a coil of wire wiggles in the field of a magnet,
a current flows in the wire.
There's your electrical signal !
Explanation:
average speed = total distance travelled / total time travelled
time to travel the first 6km: 6 / 50 = 3/25 (h)
time to travel the next 6km: 6 / 90 = 1/15 (h)
[I think there's problem in the question 'cause 900km/h sounds impossible for normal person to travel in normal condition]
The total time: 3/25 + 1/15 = 14/75 (h)
Average speed over the 12 km drive will be:

<span>D. Pressure increases with increasing depth.
This occurs because there is more weight above you to increase the pressure.
</span>
Ball 4 because the higher the elevation is the greater the potential energy it has
The moon<span> is 1/4 the size of </span>Earth<span>, so the </span>moon's<span> gravity is much less than the </span>earth's gravity, 83.3% (or 5/6) less to be exact. Finally, "weight<span>" is a measure of the gravitational pull between two objects. So of course you would </span>weigh<span> much less on the </span>moon<span>.</span>