# Topic: Physical World (Test 3)

Topic: Physical World
Q.1
In the event of your stumbling upon a discovery, which has great academic interest but is certain to have nothing but dangerous consequences for the human society. How, if at all, will you resolve your dilemma?
A. Share it with your colleagues only without publicity if there is no way to save human society from dangerous consequences. Look for ways to save the human society along with your colleagues
B. Tell every Tom Dick and Harry about it
C. Keep it to yourself.
D. Tell the media
Explaination / Solution:

If an invention that only cause harm to the society, it should be in safe hands only and the safe hands are only who discovered it. So it's better to keep the information upto you and your colleagues, so that all of them can work on it to make it useful for society.

Workspace
Report
Q.2
Strong Nuclear Force is
A. the strongest of all fundamental forces, about 100 times the electromagnetic force in strength
B. the strongest of all fundamental forces, about 10 times the gravitational force in strength
C. the strongest of all fundamental forces, about 100 times the gravitational force in strength
D. the strongest of all fundamental forces, about 10 times the electromagnetic force in strength
Explaination / Solution:

In particle physics, the strong interaction is the mechanism responsible for the strong nuclear force (also called the strong force or nuclear strong force), and is one of the four known fundamental interactions, with the others being electromagnetism, the weak interaction and gravitation. At the range of 10−15 m (femtometer), the strong force is approximately 137 times as strong as electromagnetism, a million times as strong as the weak interaction and 1038times as strong as gravitation.

Workspace
Report
Q.3
Strong Nuclear Force has
A. long range compared to gravitational forces
B. long range compared to electrical forces
C. short range compared to electromagnetic forces
D. is exerted by electromagnetic fields
Explaination / Solution:

Strong Nuclear Force : The nucleus is held by the forces which protect them from the enormous repulsion forces of the positive protons. It is a force with short range and not similar to the electromagnetic force. We know that the nucleus is made up with its fundamental particles that are the protons and neutrons. These are formed with quarks which are held together with strong force. This strong force is residual color force. The basic exchange particle is called gluon which works as mediator forces between quarks. Both the particles; gluons and quarks are present in protons and neutrons.

Workspace
Report
Q.4
The sun releases energy coming from
A. gravitational forces
B. strong nuclear forces
C. weak electrical forces
D. electromagnetic waves
Explaination / Solution:

In addition to intense heat, there is an incredible amount of pressure at the Sun's core. In fact, the vast amounts of hydrogen atoms in the Sun's core are compressed and heated so much that they fuse together. This reaction, known as nuclear fusion, converts hydrogen atoms into helium. The by-product of nuclear fusion in the Sun's core is a massive volume of energy that gets released and radiates outward toward the surface of the Sun and then into the solar system beyond it.

Workspace
Report
Q.5
Weak Nuclear Force
A. is responsible for a common form of radioactivity called beta decay
B. is responsible for holding the electrons and the nucleus together
C. is responsible for holding the electrons of the nucleus together
D. is responsible for holding the constituents of the nucleus together
Explaination / Solution:

The weak nuclear force stops a neutron from decaying into a proton and an electron. When this happens, an electron leaves the atom. This is known as beta decay.

Workspace
Report
Q.6
The difference between nuclear forces and electromagnetic forces is that
A. nuclear forces do not depend on charge
B. nuclear forces have longer range compared to electromagnetic forces
C. nuclear forces are mediated by photons compared to gluons for electromagnetic forces
D. nuclear forces are weaker compared to electromagnetic forces
Explaination / Solution:

The nuclear force does not depend upon the charge of nucleons.Nuclear forces usually depend upon the velocity of the nucleons.

Workspace
Report
Q.7
In β-decay, the nucleus emits.
A. an electron and an uncharged particle called neutrino
B. a proton and a charged particle called neutrino
C. an electron and a charged particle called neutrino
D. a proton and a charged particle called anti neutrino
Explaination / Solution:

In nuclear physics, beta decay (β-decay) is a type of radioactive decay in which a beta ray (fast energetic electron or positron), and a neutrino are emitted from an atomic nucleus. For example, beta decay of a neutron transforms it into a proton by the emission of an electron, or conversely a proton is converted into a neutron by the emission of a positron (positron emission), thus changing the nuclide type.

Workspace
Report
Q.8
The fundamental force with the shortest range is
A. Gravitational Force
B. Strong Nuclear Force
C. Weak Nuclear Force
D. Electromagnetic Force
Explaination / Solution:

There are four fundamental forces in nature which are Gravitational force, Strong force, Weak force and Electromagnetic force.

Gravitational Force: This force is the weakest but has an infinite range.

Strong Nuclear force: This force holds the nucleus of an atom together. It is the strongest of the forces. It acts over a range of about 10-15m.

Weak Nuclear Force: This force is weak compared to the strong force as the name implies and has the shortest

range of 10-18m

Electromagnetic Force: This is the second strongest force after the strong force and it acts on electrically charged particles. It has strength of 1/137 relative to the strong force but has an infinite range.

Workspace
Report
Q.9
in every conservation principle
A. a physical quantity like mass is converted into energy
B. a physical quantity changes to a form of energy
C. a physical quantity for example total momentum does not change in a phenomenon. The quantity has the same value before and after the phenomenon.
D. a physical quantity like energy is converted into mass
Explaination / Solution:

In physics, a conservation law states that a particular measurable property of an isolated physical system does not change as the system evolves over time. Exact conservation laws include conservation of energy, conservation of linear momentum, conservation of angular momentum, and conservation of electric charge.

Workspace
Report
Q.10
for motion under an external conservative force
A. the mechanical energy i.e. the kinetic energy of a body is a constant
B. the total mechanical energy i.e. the sum of kinetic and potential energy of a body is a constant only if there is no motion
C. the mechanical energy i.e. the potential energy of a body is a constant
D. the total mechanical energy i.e. the sum of kinetic and potential energy of a body is a constant