PHYSICS
Exam questions and solutions with
deep explanation.
1. Which among the following is the fundamental quantity ?
(1) Volume
(2) Time
(3) Velocity
(4) Force
Definition
The fundamental qualities of Physics are the seven basic quantities
that can be used to express all other physical quantities. These are
as follows: Length: Metre, Heat: Kelvin, Time: second, Luminous
Intensity: Candela, Mass: Kilogram, Electric Current: Ampere, and
Amount of substance: Moles.
2. When a ring of metal is heated what happens to its hole ?
(1) expands
(2) contracts
(3) it expands or contracts according to its diameter
(4) it expands or contracts according to its coefficient of expansion
Definition;
The hole size will increase because in expansion the size between
two molecules do not increase so when the molecules on the outer
edge move outward. Due to expansion, the size of the hole will also
increase so as to compensate for the distance change between the
molecules. Thermal expansion is the tendency of matter to change
in volume in response to a change in temperature. When a
,substance is heated, its particles begin moving more and thus
usually maintain a greater average separation.
3. If the diameter of a capillary is doubled, then the rise of water in
it will be (1) two times
(2) half
(3) four times
(4) no change
Definition;
. Radius of a capillary tube is inversely proportional to the height
of the liquid column. So, if the radius of the tube is doubled, the
rise in the level of water will become half of the previous rise in the
capillary tube. Capillary action, or capillarity, is the ability of a liquid
to flow in narrow spaces without the assistance of, and in
opposition to external forces like gravity. The effect can be seen in
the drawing up of liquids between the hairs of a paint-brush, in a
thin tube, in porous materials such as paper, in some non-porous
materials such as liquefied carbon fiber, or in a cell. It occurs
because of intermolecular attractive forces between the liquid and
solid surrounding surfaces.
4. Why does the needle of iron swim on the water surface when it is
kept gently ?
(1) It will remain under the water, when it will displace more water
than its weight
(2) the density of needle is less than that of water
(3) due to surface tension
(4) due to its shape
Definition;
According to Archimedes' principle, we can note that the amount
of water displaced by a needle is lesser than the amount of water
moved out by the needle (that is displacement of the needle). So
the needle initially stays on the surface of the water and then sinks
into the water. Surface tension is a contractive tendency of the
, surface of a liquid that allows it to resist an external force. It is
revealed, for example, in the floating of some objects on the
surface of water, even though they are denser than water, and in
the ability of some insects (e.g. water striders to run on the water
surface. This property is caused by cohesion of similar molecules,
and is responsible for many of the behaviors of liquids.
5. The mass of a star is two times the mass of the Sun. How will it
come to an end ?
(1) Neutron Star
(2) Black hole
(3) White Dwarf
(4) Red Giant
Definition;
The mass of a star which is two times the mass of the sun turns
into a neutron star. A neutron star is a type of stellar remnant that
can result from the gravitational collapse of a massive star during a
Type II, Type Ib or Type Ic supernova event. Such stars are
composed almost entirely of neutrons, which are subatomic
particles without electric charge and with slightly larger mass than
protons. Neutron stars are very hot and are supported against
further collapse by quantum degeneracy pressure due to the
Pauli’s exclusion principle. This principle states that no two
neutrons (or any other fermionic particles) can occupy the same
place and quantum state simultaneously. A typical neutron star has
a mass between about 1.4 and 3.2 solar masses ( Chandrasekhar
Limit), with a corresponding radius of about 12 km if the Akmal–
Pandharipande–Ravenhall equation of state (APR EOS) is used.
6. Rain drops fall from great heights. Which among the following
statements is true regarding it?
(1) they fall with that ultimate velocity, which is different for
different droplets
(2) they fall with the same ultimate velocity.
3) their velocity increases and they fall with different velocity on the
earth
Exam questions and solutions with
deep explanation.
1. Which among the following is the fundamental quantity ?
(1) Volume
(2) Time
(3) Velocity
(4) Force
Definition
The fundamental qualities of Physics are the seven basic quantities
that can be used to express all other physical quantities. These are
as follows: Length: Metre, Heat: Kelvin, Time: second, Luminous
Intensity: Candela, Mass: Kilogram, Electric Current: Ampere, and
Amount of substance: Moles.
2. When a ring of metal is heated what happens to its hole ?
(1) expands
(2) contracts
(3) it expands or contracts according to its diameter
(4) it expands or contracts according to its coefficient of expansion
Definition;
The hole size will increase because in expansion the size between
two molecules do not increase so when the molecules on the outer
edge move outward. Due to expansion, the size of the hole will also
increase so as to compensate for the distance change between the
molecules. Thermal expansion is the tendency of matter to change
in volume in response to a change in temperature. When a
,substance is heated, its particles begin moving more and thus
usually maintain a greater average separation.
3. If the diameter of a capillary is doubled, then the rise of water in
it will be (1) two times
(2) half
(3) four times
(4) no change
Definition;
. Radius of a capillary tube is inversely proportional to the height
of the liquid column. So, if the radius of the tube is doubled, the
rise in the level of water will become half of the previous rise in the
capillary tube. Capillary action, or capillarity, is the ability of a liquid
to flow in narrow spaces without the assistance of, and in
opposition to external forces like gravity. The effect can be seen in
the drawing up of liquids between the hairs of a paint-brush, in a
thin tube, in porous materials such as paper, in some non-porous
materials such as liquefied carbon fiber, or in a cell. It occurs
because of intermolecular attractive forces between the liquid and
solid surrounding surfaces.
4. Why does the needle of iron swim on the water surface when it is
kept gently ?
(1) It will remain under the water, when it will displace more water
than its weight
(2) the density of needle is less than that of water
(3) due to surface tension
(4) due to its shape
Definition;
According to Archimedes' principle, we can note that the amount
of water displaced by a needle is lesser than the amount of water
moved out by the needle (that is displacement of the needle). So
the needle initially stays on the surface of the water and then sinks
into the water. Surface tension is a contractive tendency of the
, surface of a liquid that allows it to resist an external force. It is
revealed, for example, in the floating of some objects on the
surface of water, even though they are denser than water, and in
the ability of some insects (e.g. water striders to run on the water
surface. This property is caused by cohesion of similar molecules,
and is responsible for many of the behaviors of liquids.
5. The mass of a star is two times the mass of the Sun. How will it
come to an end ?
(1) Neutron Star
(2) Black hole
(3) White Dwarf
(4) Red Giant
Definition;
The mass of a star which is two times the mass of the sun turns
into a neutron star. A neutron star is a type of stellar remnant that
can result from the gravitational collapse of a massive star during a
Type II, Type Ib or Type Ic supernova event. Such stars are
composed almost entirely of neutrons, which are subatomic
particles without electric charge and with slightly larger mass than
protons. Neutron stars are very hot and are supported against
further collapse by quantum degeneracy pressure due to the
Pauli’s exclusion principle. This principle states that no two
neutrons (or any other fermionic particles) can occupy the same
place and quantum state simultaneously. A typical neutron star has
a mass between about 1.4 and 3.2 solar masses ( Chandrasekhar
Limit), with a corresponding radius of about 12 km if the Akmal–
Pandharipande–Ravenhall equation of state (APR EOS) is used.
6. Rain drops fall from great heights. Which among the following
statements is true regarding it?
(1) they fall with that ultimate velocity, which is different for
different droplets
(2) they fall with the same ultimate velocity.
3) their velocity increases and they fall with different velocity on the
earth
