How long will it take a 1500 W motor to lift a 300 kg piano to a sixth-story window 20 m above?
2 answers:
It will take the motor 39.2 seconds to lift the piano to the sixth-story window.
<u>Given the following data;</u>
- Power = 1500 Watts
- Mass = 300 kg
- Height = 20 meters
We know that acceleration due to gravity is equal to 9.8 m/s².
To find how long it will take to lift the piano to the sixth-story window;
First of all, we would have to determine the gravitational potential energy required to lift the piano up.
Mathematically, gravitational potential energy is given by the formula;
where:
G.P.E is the gravitational potential energy of an object.
m is the mass of the object.
g is the acceleration due to gravity.
h is the height of the object.
Substituting into the formula, we have;
G.P.E = 58,800 Joules
Next, we would determine the time using the following formula;
Substituting the values into the formula, we have;
<em>Time = 39.2 seconds.</em>
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Answer:
which agrees with option"B" of the possible answers listed
Step-by-step explanation:
Notice that in order to solve this problem (find angle JLF) , we need to find the value of the angle defined by JLG and subtract it from , since they are supplementary angles. So we focus on such, and start by drawing the radii that connects the center of the circle (point "O") to points G and H, in order to observe the central angles that are given to us as
and
. (see attached image)
We put our efforts into solving the right angle triangle denoted with green borders.
Notice as well, that the triangle JOH that is formed with the two radii and the segment that joins point J to point G, is an isosceles triangle, and therefore the two angles opposite to these equal radius sides, must be equal. We see that angle JOH can be calculated by :
Therefore, the two equal acute angles in the triangle JOH should add to:
resulting then in each small acute angle of measure
.
Now referring to the green sided right angle triangle we can find find angle JLG, using:
Finally, the requested measure of angle JLF is obtained via:
