Aristotle's geocentric theory failed to match the expected predictions because a few celestial objects appear to have retrograde motion.
Answer: Option B
<u>Explanation:</u>
Aristotle’s theory states that all the bodies in universe rotate around the earth, and earth is located at the centre. But, the most serious challenge it was given was that, the difference found in the paths of revolution of mercury and Venus. They are revolving around the sun, and not the earth, periodically.
This is the significant drawback, and major factor for the Copernicus and the other models to be achieved. The mercury and Venus, closest planets to earth, and the sun too, are not following the earth’s path. And hence, upon studying clearly, all celestial bodies do not follow a path round the earth, but around a fireball, that is sun.
Given,
Mass of the ball (m) = 1.50 x 10³ kg = 1500 kg
Height raised = Displacement of the ball (D) = 40.0 m
Time taken (t) = 20 seconds
Power = Work done(W) ÷ time taken (t)
Work done (W) = Force (F) x Displacement (D)
Force (F) = Mass (m) x Acceleration due to gravity (g)
Acceleration due to gravity for earth (g) = 9.81 m/s²
Therefore,
Force (F) = 1500 x 9.8 = 14715 N
Work done = Force x Displacement = 14715 x 40 = 588600 Joules
Now,
Power = Work done ÷ time taken = 588600 ÷ 20 = 29430 Watts
Explanation:
760 mmHg (millimeters of mercury) is a measure of atmospheric pressure. It represents the height of a column of mercury at which the static pressure at the bottom is equal to the atmospheric pressure.
1 atm = 760 mmHg = 101,325 Pa = 14.7 psi
Answer:
0 N, 3.49 m/s
Explanation:
Draw a free body diagram for the bucket at the top of the swing. There are two forces acting on the bucket: weight and tension, both downwards.
If we take the sum of the forces in the radial direction, where towards the center is positive:
∑F = ma
W + T = m v² / r
The higher the velocity that Rony swings the bucket, the more tension there will be. The slowest he can swing it is when the tension is 0.
W = m v² / r
mg = m v² / r
g = v² / r
v = √(gr)
Given that r = 1.24 m:
v = √(9.8 m/s² × 1.24 m)
v = 3.49 m/s