If one knows only the constant resultant force acting on an object and the time during which this force acts, one can determine
1 answer:
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Answer:
Approximately .
Explanation:
Note that the electric rate in this question is in the unit dollar-per-, where
is the energy to run an appliance of power
for an hour.
Number of minutes for which the air conditioner is running in that day: . Apply unit conversion and ensure that this time is measured in hours (same as the unit of the electric rate.)
.
The power of this air conditioner is:
.
Thus, the energy that this air conditioner would consume would be:
.
At a rate of dollar-per-
, the cost of that much energy would be approximately
dollars (rounded to the nearest cent.)
Answer:
20m
6.9s
Explanation:
The vertical velocity of the ball is 20m/s. We can calculate the kinetic energy which gets transferred to potential energy once it gets to the top.
we can subtitute v = 20m/s and g = 10m/s2
So the ball could go 20m high from the child hand, or 120m fro the bottom of the cliff.
The time it takes for the ball to travels to the top is the time it takes for it to decelerate from 20m/s to 0m/s with gravitational deceleration g = 10m/s2
t = v / g = 20 / 10 = 2s
Then the ball will start accelerating down ward with a constant acceleration of g = 10m/s. In order to cover distance d of 120m from the top to the bottom of the cliff
So the total time it takes is 4.9 + 2 = 6.9s