Answer:
The theory of relativity usually encompasses two interrelated theories by Albert Einstein: special relativity and general relativity, proposed and published in 1905 and 1915, respectively. Special relativity applies to all physical phenomena in the absence of gravity. General relativity explains the law of gravitation and its relation to other forces of nature.It applies to the cosmological and astrophysical realm, including astronomy.
The theory transformed theoretical physics and astronomy during the 20th century, superseding a 200-year-old theory of mechanics created primarily by Isaac Newton. It introduced concepts including spacetime as a unified entity of space and time, relativity of simultaneity, kinematic and gravitational time dilation, and length contraction. In the field of physics, relativity improved the science of elementary particles and their fundamental interactions, along with ushering in the nuclear age. With relativity, cosmology and astrophysics predicted extraordinary astronomical phenomena such as neutron stars, black holes, and gravitational waves
Yes a kg of hydrogen will have more atoms than a kg of lead, because lead has a higher atomic mass, than hydrogen so it will take more atoms of hydrogen to make a kg than lead
Answer:
The strength of the magnetic field decreases as a result of removing one of those batteries.
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Explanation:
Given that,
Radius of the disk, r = 0.25 m
Mass, m = 45.2 kg
Length of the ramp, l = 5.4 m
Angle made by the ramp with horizontal, 
Solution,
As the disk starts from rest from the top of the ramp, the potential energy is equal to the sum of translational kinetic energy and the rotational kinetic energy or by using the law of conservation of energy as :
(a) 
h is the height of the ramp


v is the speed of the disk's center
I is the moment of inertia of the disk,






v = 4.52 m/s
(b) At the bottom of the ramp, the angular speed of the disk is given by :



Hence, this is the required solution.