7) c
opposite charges attract, equal charges repell
8) c
Followed from equation
9) d
Same reason as under 7
How fast a car goes is known as its speed.
Speed = (distance covered) divided by (time to cover the distance)
It has nothing to do with the direction the car is going.
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The car's velocity is its speed AND the direction it's going.
30 miles per hour . . . speed
40 miles per hour north . . . velocity
20 miles per hour south
20 miles per hour west . . . . . same speed, different velocity
-- 'Velocity' is NOT a big word that you use when you mean
'speed' but you want to sound smarter. It's a different thing.
-- If you don't know anything about the direction the car is going,
then you can't say anything about its velocity.
-- If the car is going around a curve, then its velocity is constantly
changing, even if its speed is constant.
Well, "speed" normally = (total distance covered) / (time to cover the distance).
In this case, we don't know the total distance that Santa has traveled, so the question can be answered only if we're willing to consider some other meaning of "speed".
Maybe we could say that in this case, "speed" means the average rate at which he visits houses. Then ...
Speed of visits = (total houses visited) / (time to visit them).
Speed of visits = (800 million houses) / (48 hours)
Speed of visits = 16.67 million houses per hour.
That's 277.8 thousand houses per minute
That's <em>4,630 houses per second</em>
Answer:
The potential energy increases and the kinetic energy decreases
