How long will it take an object dropped from a window to fall a distance of 78.4 meters?

The time is 4 sec.

Step-by-step explanation:

Given that,

Distance = 78.4 m

We need to calculate the time

Using equation of motion

Where, s = distance

g = acceleration due to gravity

t = time

Hence, The time is 4 sec.

this is answer of 144 cubic meters

- "runner b is moving at a slower rate."

- "the graphs shown are graphs of distance(km) against time(min).

the slopes of this graphs are are given by:

slope = (change in y)/(change in x)

= (change in distance)/(change in time)

this is the formula for finding the speed. so, the slope of these graphs represent the speed of the runner.

taking each division in the graph to represent 1 on both axis:

runner a ⇒ speed = (2-0)/(1-0)

= 2/1

= 2 km/min

runner b ⇒ speed = (3-0)/(3-0)

= 3/3

= 1 km/min

this shows that   runner b is moving at a slower rate."