PHYSICS | HSEB NOTES | SHORT QUESTION ANSWER
UNIT 1 : MECHANICS
LESSON 1 : UNITS AND MEASUREMENT OF PHYSICAL QUANTITIES
CLASS : 11
UNIT 1 : MECHANICS
LESSON 1 : UNITS AND MEASUREMENT OF PHYSICAL QUANTITIES
CLASS : 11
Following are some question from Units and measurement :
Q.1. Can we tell the unit of a physical quantity from its
dimension ?
Ans. => Yes, we can tell the unit of a physical quantity.
For example, if a physical quantity has the dimension [MoLT-1],
its SI-unit will be ms-1.
Q.2. Can dimension analysis tell you that a physical
relation is completely right ?
Ans. => No. it can not tell the relation completely
correct. It is because that the numerical factor in the relation can not be
determined.
Q.3. What is the importance if base units ?
Ans. => There are seven base units in SI-units. All the
physical quantities can be expressed in terms of there base units.
Q.4. Do all the constants carry dimension ?
Ans. => No, all the constants do not carry dimensions but
some constants carry dimensions. For example : G is a constant which has a
dimensiion.
Q.5. Does the measurement if a physical quantity depend upon
the system if units used ?
Ams. => It does not depend on the system of units. There
is only change in the numerical value of the physical quantity.
Q.6. Can a physical quantities have unit but is
dimensionless ?
Ams. => Yes, it is possible to have unit but no
dimension. For example angle has no dimension but has the uni of radian.
Q.7. Which physical quantities have the same dimension of
[ML-1T-2] ?
Q.8. Is dimensionally correct equation necessarily to be a
correct physical relation ? What about dimensionally wrong equation ? [HSEB
2063]
Ans. => Even if a physical relation is dimensionally
correct, it doesn’t prove that the relation is completely correct. It is
because the numerical factor in the relation can be wrong. Dimensionally wrong
equation has no meaning.
Q.9. What are characteristics of a physical standard ?
Ans. => A physical standard must have following
characteristics :
- Invariablity
- Accessibility
- Indestructibility
- reproduciblity
Q.10. Do you think that a defination of a physical quantity
for which no direct method of measurement is known or given has a physical
meaning ?
Ans. => Yes, the measurement may be made by indirect
method.
Q.11. Can you suggest a way to measure length along a curved
line ?
Ans. => The length along a curved line may be measured by
the technique of trajactory or by measuring the length of string by placing it
on the curved line.
What is difference between accurate and precise measurements?
ReplyDeleteWhat is difference between accurate and precise measurements?
ReplyDeleteaccurate measurement means how close the measurement is with the true value and precise measurement means how close the different measurement are.
DeleteCan an object with constant acceleration reverse its direction ?Explain..
DeleteWhat are the limitations of dimensional analysis?
ReplyDelete