PLZ HELP ME TO SOLVE THESE QUESTIONS
1. How do we bend our elbows?
2. What is a ball and socket joint?
3. Name the type of the joint in your hand which helps you to grasp a badminton
racquet?
4. Differentiate between bones and cartilage?
5. Why is the upper part of the human ear not as soft as the lower part or the
earlobe?
6. What are the things you need to take care of while measuring length?
7. How will you measure a curved line?
8. Give examples of 3 types of motions.
9. Use an activity to explain that light travels in a straight line.
10. Betty was asked to create a shape that would give a circular shadow if held in
one way and a rectangular if held another way?
11. We see the moon shining in the sky, then why is it called non-luminous?
Answers
1. The link between the humerus and the two forearm bones is the main elbow joint, which bends and straightens the arm.
2. Ball and socket joints are a type of synovial joint where the spheroid articular surface of one bone sits within a cup-like depression of another bone.
3. Our fingers have hinge joint that helps to grasp the things like a badminton racquet.
4. ✧ BONES :-
Bones are the hard, inelastic and a tough organ that forms part of the vertebral skeleton.
✧ CARTILAGE:-
Cartilage is a soft, elastic and flexible connective tissue that protects the bone from rubbing against each other.Cartilage cells are known as chondrocytes.
5. The upper part of ear not as soft as ear lobe because the upper portion of the ear is made up of cartilage and ear lobe does not contain any cartilage. Cartilages are parts of the human skeleton system but they are not as hard as bones. These can be easily bent. Cartilage are also present in human's nose.
6. The following things should be kept in mind while measuring the length of any object:-
- The object to be measured should be kept properly on the scale such that one of its end coincides with the zero (0) mark on the scale.
- The object to be measured should be kept parallel to the scale and touching it.
7. The length of a curved line can be measured by using a thread and a scale. (1) We take a piece of thread and put a knot near its one end. This knot will act as a starting point for measuring the length of the curved line .
8. Examples of different types of motion :-
Circular -:
- a) Motion of satellites around planets.
- b) Motion of car turning to a curved track
Rotational-:
- a) Motion of giant wheel
- b) Motion of wheels of moving vehicle
Periodic-:
- a) Motion of simple pendulum.
- b) Motion of Earth on its own axis.
9. Two experiments are used to demonstrate how light travels in straight lines. In the first example, the presenter arranges three pieces of card, with holes in, in an uneven line. The light stops and cannot travel through all three cards. When she arranges the holes in a straight line, the light can travel through
10. Yes, a cylindrical shape is the one that would give a circular shadow if held in one way and a rectangular shadow if held in another way. Its circular ends will form a circular shadow when kept in the way of light whereas its curved sides will give rectangular shadow.
11. Moon doesn't give off light of its own, that's why the moon is considered a non-luminous body. All its light we see is reflected from the sun and to a very minor effect, from the reflection of sunlight off the earth.