C. Short answer questions.
1. What is the need to know the distances? Give three reasons.
2. Give three examples where knowledge of distance is necessary.
3. Give a list of quantities that need to be measured in everyday life.
4. Why cannot hand span be used as a standard unit of length measurement?
5. Why is a standard unit of measurement of length required?
6. What is measurement? What is the need for correct measurements?
the other end it is 57.2 cm. What is the length of the box?
7. While measuring the length of a cardboard box, the reading of the scale at one end is 5.6 cm 2002
8. Distinguish between rectilinear and curvilinear motion.
9. How is the motion of a moving wheel of a bicycle different from that of a moving fan?
10. All oscillatory motions are periodic motions. Explain.
Answers
Answer:
1. We need to measure distance because it is needed to calculate other things like speed, time taken in a journey and much more... It helps us to make decisions based on the outcome of distance (it's a very important thing when it comes to travel in space).
2. 1)To know the distance between places. 2)To know time taken by object to cover following distance. 3)To know the average velocity need by object to cover distance in given unit of time.
3.Mass: When we purchase an item in the grocery shop we used ask for the weigh of the item for example: Two kilograms of doordal. ...
Time: We usually asks about the time in every situation.
Electric current: At the end of every month we will get the electricity bill which we consume in house or in any other place.
4. Hand span and cubit are not used as standard units of length because their sizes vary from person to person. So, two different persons may give different measurements for the same length, which is not desirable for a standard unit.
5.A unit of measurement which has a fixed value which does not change from person to person or place to place, is called a standard unit of length. It is necessary to have standard units of measurements for the sake of uniformity in measurements.
6. It means the measurement of distance, mass and time is necessary for the description of the natural phenomena. The need for measurement is clear from the following examples are: 1. we can find the speed if we can measure the distance travelled and time taken to travel that distance.
7. 57.2-5.6= 51.6
8. In rectilinear motion the body travels in a straight line whereas in curvilinear motion the body travels in a curved path. In rectilinear motion the body can travel with uniform velocity whereas in curvilinear motion the velocity keeps changing as the direction keeps changing.
9. Wheels of a moving bicycle show rectilinear motion and circular motion. Because when the wheel is rotating, it also moves the bicycle forward (unless breaks are applied). A blades of moving fan only show circular motion, as it doesn't make the fan move from place to place.
10. All oscillatory motions are periodic because each oscillations gets completed in a definite interval of time. Eg: On being pulled and then released, a load attached to a spring executes oscillatory motion. On the other hand, all periodic motions may not be oscillatory.
Explanation:
Hope this answer will help you.✌️