Answer:
a) 16 N
b) 2.13 m/s²
Explanation:
Draw a free body diagram of the tv stand. There are four forces:
Weight force mg pulling down,
Normal force N pushing up,
Friction force Nμ pushing left,
and applied force P pulling right.
Sum of forces in the y direction:
∑F = ma
N − mg = 0
N = mg
The net force in the x direction is:
∑F = P − Nμ
∑F = P − mgμ
∑F = 25 N − (7.5 kg) (10 m/s²) (0.12)
∑F = 16 N
Net force equals mass times acceleration:
∑F = ma
16 N = (7.5 kg) a
a = 2.13 m/s²
B) atmosphere pressure, i believe
The subatomic particles that acts like a mini-magnet is electron. Electrons are negatively charged sub atomic particles in an atom. The electron spin is a property of an electron that makes it behave like it's spinning; a spinning electron produces a magnetic field that makes it behave like a tiny magnet in an atom.
Gas Clouds (of Hydrogen), starts contracting under the influence of gravitational pull of gas.
As it's contracting, it's pressure & temperature increases, it is called "Protostar" now.
When Temperature become sufficiently high (4 million C), Nuclear fusion starts, & large amount of energy releases.
Energy Travels to star's surface and is radiated in the form of light, heat & EM Radiation.
The contraction of star stops only when "Inward Gravitational pull" is balanced by "Outward Radiant Energy". At this time, star becomes stable in size & temperature.
Contraction continues, 'causes star's outer region to 'boil' & 'expand'. At this stage, it becomes brightest, red giant.
As fuel burns, helium nuclei fuses & form Carbon nuclei further to silicon & further to Iron Nuclei by progressive Nuclear Fusions. At all this stages, star was very unstable.
Star end it's life in many different way & it depends on it's mass, whether it ends as "White Dwarf", "Neutron Star" or "Supernova"
This was a short note on life story of star. <span>Hope this helps!</span>
