101.6\(\times\)10⁶

19.4

The distance of the planet from the Earth
d = 6.3\(\times\)10¹⁰ m
Time t = 7 minutes = 7\(\times\)60 s.
The speed of signal v = ?
The speed of signal v = \({2d\over t}={2\times 6.3 \times 10^8\over 7\times 60}=3\times 10^8 ms^{-1}\)

Parallax is the name given to the apparent change in the position of an object with respect to the background, when the object is seen from two different positions.

Astronomical telescopes are used to study the motion of planets and other heavenly bodies in the sky. Radio telescopes have enabled the astronomers to observe distant points of the universe. Studies of the universe are done using physical principles.

Technology is the application of the principles of physics for practical purposes. The application of knowledge for practical purposes in various fields to invent and produce useful products or to solve problems is known as technology

The study of forces acting on bodies whether at rest or in motion.

Unification and Reductionism are the two approaches in studying physics.

(i) 10¹ = deca and its symbol is da
(ii) 10⁶ = mega and its symbol is M
(iii) 10¹²= tera and its symbol is T
(iv) 10^-1 = deci and its symbol is d
(v) 10^-6 = micro and its symbol is \(\mu\)
(vi) 10^-12= pico and its symbol is p

(i) The unit in which the quantity is measured
(ii) The numerical value or the magnitude of the quantity (n), the number of times that unit (u) is contained, in the given physical quantity. Q = nu.

(i) Mechanics is a branch of physics.
(ii) It is divided into statics and Dynamics.
(iii) Mechanics deals with the study of motion of particles, deformable bodies and general system of particles.

(i) Physics is a branch of science.
(ii) The word comes from a Greek word meaning 'nature'.
(iii) It deals with the study of nature and natural phenomena.

Least count of screw gauge
\(={{Pitch}\over{No. of\ divisions}}\)
\(={{1}\over{100}}=0.01\ mm\) (or) 0.001 cm
Least count of vernier calipers
\(=1MSD-1-1VSD=(1-19/20)MSD\)
\(={{1}\over{20}}\) = 0.05 cm.
So screw gauge is more precise than vernier.

The distances of astronomical objects like stars, planets etc from the earth are huge. The distance on the earth are relatively small so it can be measured in km, m.
For Example:
The distance to be next nearest big galaxy Andromeda is  21,000,000,000,000,000,000 km.
i.e. 21\(\times\)10¹⁸ km.
This no is so large that it becomes hard to write and to interpret.
So astronomical units like the light year, parsec A.U for large distances.

Angle \(\theta\) = 1° 55'= 115' = (115\(\times\)60)"\(\times\) (4.85\(\times\) 10^-6) rad = 3.34\(\times\)10^-2 rad
Since 1" = 4.85\(\times\)10^-6 rad
Radius of the Earth = 6.4\(\times\)10⁶m
From the Figure AB is the diameter of the Earth (b) = 2\(\times\)6.4\(\times\)10⁶m
Distance of the Moon from the Earth x = ?
\(x={b\over \theta}={2\times 6.4 \times 10^6\over 3.34\times 10^{-2}}\)
x = 3.83\(\times\)10⁸m