Answer:
The velocity of a falling object
Explanation:
The positive X axis is towards right and positive Y axis is towards up, so North direction is positive
A vector with less than 1 magnitude is not negative, because its magnitude may be in between 0 and 1 which is positive vector.
Any vector whose magnitude is greater than 1 is never be a negative vector.
The velocity of a falling object is towards bottom, that is towards negative Y axis. So that vector is negative.
The widely accepted hypothesis before that turned out wrong was the Earth-Centered theory or the Geocentric Theory. This was proposed by the philosopher Ptolemy. He came about to this hypothesis from hi observation that from the Earth's perspective, the celestial bodies like the Sun, stars and the moon, look like they rotate around the Earth each day and night. However, this was disproved by Galileo Galelei by his Heliocentric Theory. He observed through the telescope that the Venus also changes phases like the moon. However, he deduced that this is not possible from the positions of the Venus, Earth, Moon and Sun.
Answer:
Efficiency of a machine is how well the machine works and what the machine is capable of doing.
Mechanical advantage=Load/Effort.
720/180=4
Answer:
Explanation:
Stefan's formula for emission of radiation is
E = e σ A ( T⁴ - T₀⁴ )
E is energy radiated , e is emissivity , σ is stefan's constant , T is temperature of object and T₀ is temperature of surrounding. A is area of surface .
E = .35 x 5.67 x 10⁻⁸ ( 298⁴ - 268⁴ ) x 4π x .25²
= 1.9845 x 10⁻⁸ ( 78.86 - 51.58 ) x 10⁸ x .0625
= 3.38 J /s
