Monday 25 January 2016
class6 movements
Class 6 Science
Lesson-9 Movements in the body
Q/Ans.
Q1. Enumerate the functions of the
skeletal system in our body.
Ans: The
functions of the skeletal system in our body are:
1.
It
forms the framework of our body, provides shape and support and holds the body
upright.
2.
It
helps in the movement of various parts of the body.
3.
It
protects the internal organs of our body.
4.
Bones
are filled with spongy mass called bone marrow where blood cells are formed.
Q2. What are the functions of the
ribcage?
Ans: The
functions of the ribcage are:
1.
It
protects our important organs such as the heart and the lungs.
2.
It
also protects the parts of the stomach and kidneys.
Q3. What are the functions of the
spine?
Ans: The
functions of the spine are:
1.
It helps in supporting our skeleton.
2. It also helps in bending and twisting our
back.
Q4. Describe with examples the four
movable joints in our body.
Ans: The
four movable joints in our body are:
1.
Hinge
joint:
·
They
allow movement in only two directions-backward and forward or upward and
downward like hinges on the door.
·
Example:
elbow and knee joint.
2.
Ball
and socket joint:
·
In
this joint, a ball like end of one bone fits into a cup-shaped socket of the
other bone.
·
They
allow maximum movement in all the directions.
·
Example:
hip and shoulder joint.
3.
Pivot
joint:
·
It
allows sideways as well as up- down movement.
·
Example:
It is found in the neck.
4.
Gliding
joint:
·
They
help the back to bend and twist.
·
Example:
ankles and wrists.
Q5. Mention the role of X-rays in the
field of medicine.
Ans:
1. It is possible to see the images in a
living being using radiations called X- RAYS.
2. Doctors can identify the bone injury with
the help of X- rays.
Class7 light
Class 7 Science
Lesson-15 Light and Associated Phenomena
I. Answer the following questions in
brief.
1. What is
reflection of light?
Ans.
When light falls on an object, it changes
its direction and bounces back. This bouncing back of lightis known as reflection of light
2. Define
the following terms:
a) Incident ray b) Reflected ray c) Principal focus d) Normal e) Point of incidence
Ans.
a)
Incident ray- the ray of light that falls on the surface of the reflecting
material or mirror.
b) Reflected ray- the ray of light that
is sent back from the surface of the reflecting surface.
c) Principal focus- all the rays of
light reflected from the curved surface of a concave mirror meet at
a point. This point is called the
principal focus.
d) Normal- the perpendicular line drawn
from the point of incidence on the reflecting surface.
e) Point of incidence- the point at
which the light ray strikes the reflecting surface.
3. What do
you mean by lateral inversion?
Ans.
In the image formed by a plane mirror
there is an interchange of left and right. This is called lateral
inversion.
II. Answer the following questions in
detail.
1. What are
regular and irregular reflections? Explain with the help of diagrams.
Ans.
Smooth, shiny surfaces have a regular reflection: After reflection
all rays travel in the same direction
Rough,
dull surfaces have a diffused reflection.
Diffused reflection
scatters light in different directions
and help
us to see things.
2. With the help of an activity, prove that light
travels in a straight line.
Ans.
Take three cardboards A, B and C and
make a pinhole at their centers. Place a burning candle on one side of A and
arrange the cardboards in such a way that the three pinholes and the candle
flame are in a straight line. The candle flame will be visible through the
pinhole of the cardboard C.
Now slightly
displace any one of the cardboards and try to see the flame through the pinhole
of the cardboard C. The flame will not be visible. From this it is clear that
light travels in a straight line.
Subscribe to:
Posts (Atom)