Answer:
10.85 m/s
Explanation:
m = 1200 kg, h1 = 19 m, h2 = 13 m
Let v be the velocity
Use the conservation of energy
Potential energy at 19 m = Potential energy at 13 m + kinetic energy
m x g x h1 = m x g x h2 + 1/2 mv^2
m x g (h1 - h2) = 0.5 x m v^2
g (h1 - h2) = 0.5 v^2
9.8 (19 - 13) = 0.5 x v^2
v = 10.85 m/s
Answer: C
C. Place plastic around the metal wires, because electric charges
hardly move in plastic.
To be honest with you, there's not enough information here to calculate
the answer, because we don't know the power consumption of the front
porch light. The best we can do is represent that as a variable ... pick a
catchy name for it, which will show up in the final answer, and then you
can 'plug in' (get it ?) whatever size light bulb you want to use over the
front porch.
OK. First we have to give it a name. I could use a single letter, but
that's what everybody else always does. Remember ... this is going to
represent the power (watts) consumed by the front porch light when it's
turned on. It's the symbol that means "Front Porch Light Power" wherever
you see it. I could easily call it x or y or z, but I'm going to call it " FPLP ".
OK. FPLP = power consumption of the light, in watts .
0.001 FPLP = power consumption of the light, in kilowatts (kW).
(1 week) · (7 day/week) · (24 hour/day) = 168 hours .
Energy = (power) · (time) = (0.001 FPLP) · (168 hr) = 0.168 FPLP kWhours
Cost = ($0.17 per kWh) · (number of kWh) = (2.86¢) · (FPLP) .
There it is !
For an example, if you use a 100-W bulb in the front porch light,
then FPLP=100 W. If you leave it on 24/7 for a whole week, then
it's going to cost
(2.86¢) · (FPLP) = (2.86¢) · (100 W) = $2.86
Answer:
A (2066,6 N)
Explanation:
Use the Work formula
62.000J = F . 30
62.000/30 = 2066,6 N
The amout of time it took to move the rock doesn´t matter at all.
It is called a distraction variable, We don´t need it to solve the problem it is there just to confuse.
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