Answer:
melting polar icecaps seems the best, hopes this helps!
See the attached picture:
Answer:
The thrown rock strike 2.42 seconds earlier.
Explanation:
This is an uniformly accelerated motion problem, so in order to find the arrival time we will use the following formula:

So now we have an equation and unkown value.
for the thrown rock

for the dropped rock

solving both equation with the quadratic formula:

we have:
the thrown rock arrives on t=5.4 sec
the dropped rock arrives on t=7.82 sec
so the thrown rock arrives 2.42 seconds earlier (7.82-5.4=2.42)
"The total distance traveled divided by the time it takes to travel the distance"
That's actually a pretty good definition of average speed. <em>(A)</em>
Direction. Velocity is a vector that describes both speed and direction, while speed is a scalar that describes only speed regardless of direction.