Answer
Verified
357k+ views
Hint:In a clock, there is one second-hand which measures each second and then a minute-hand which measures minute and later a smallest one hour-hand which measures hour. We will use the concept of second-hand which completes a full angle of $2\pi $ radians in one minute or we can say it covers $2\pi $ radians in $60$ seconds.
Formula used:
Angular velocity is given by $\omega = \dfrac{{Angl{e_{total}}}}{{Tim{e_{taken}}}}$
Linear velocity is given by $v = r\omega $ where $r$ is radius of circular path.
Average acceleration is given by ${a_{average}} = \dfrac{{\Delta v}}{t}$
Instantaneous acceleration is given by $a = {\omega ^2}r$
Complete step by step answer:
Let us examine each option one by one. Since, the total angle covered by second-hand is $2\pi $ radians and time taken is a total $60$ seconds.So, using formula of angular velocity we have,
$\omega = \dfrac{{Angl{e_{total}}}}{{Tim{e_{taken}}}}$
$ \Rightarrow \omega = \dfrac{{2\pi }}{{60}}$
$ \Rightarrow \omega = \dfrac{\pi }{{30}}\,rad\,{\sec ^{ - 1}}$
So, option (B) is correct.
Now, using formula of linear velocity we have, $v = r\omega $ where $r$ is length of second-hand and it’s given as $r = 1m = 100cm$ and we find $\omega = \dfrac{\pi }{{30}}rad{\sec ^{ - 1}}$ so,
$v = r\omega $
$\Rightarrow v = 100 \times \dfrac{\pi }{{30}}$
$\Rightarrow v = \dfrac{{10\pi }}{3}\,cm\,{\sec ^{ - 1}}$
So, option (A) is correct.
Now, using formula of average acceleration ${a_{average}} = \dfrac{{\Delta v}}{t}$ we have, at $t = 15\min $ since linear velocity is independent of time and has a constant magnitude so, $\Delta v = 0$
$ \Rightarrow {a_{average}} = 0$
So, option (C) is correct.
Now, using the formula of instantaneous acceleration we have, $a = {\omega ^2}r$ where,
$\omega = \dfrac{\pi }{{30}}rad{\sec ^{ - 1}}$ And $r = 1m = 100cm$ we get,
$\Rightarrow a = \dfrac{\pi }{{30}} \times \dfrac{\pi }{{30}} \times 100$
$\therefore a = \dfrac{{{\pi ^2}}}{9}\,cm\,{\sec ^{ - 2}}$
So, option (D) is correct
Hence, the correct options are A, B,C and D.
Note:It should be remembered that, all the second-hand minute-hand and hour-hands of the clock rotate in circular direction and the basic unit of conversions are $1m = 100cm$ a complete angle in two dimensional Cartesian plane is of ${360^0}$ which thus in units of radian is written as $2\pi radians$ Also, minute hand covers an angle of $2\pi radians$ in $3600$ seconds.
Formula used:
Angular velocity is given by $\omega = \dfrac{{Angl{e_{total}}}}{{Tim{e_{taken}}}}$
Linear velocity is given by $v = r\omega $ where $r$ is radius of circular path.
Average acceleration is given by ${a_{average}} = \dfrac{{\Delta v}}{t}$
Instantaneous acceleration is given by $a = {\omega ^2}r$
Complete step by step answer:
Let us examine each option one by one. Since, the total angle covered by second-hand is $2\pi $ radians and time taken is a total $60$ seconds.So, using formula of angular velocity we have,
$\omega = \dfrac{{Angl{e_{total}}}}{{Tim{e_{taken}}}}$
$ \Rightarrow \omega = \dfrac{{2\pi }}{{60}}$
$ \Rightarrow \omega = \dfrac{\pi }{{30}}\,rad\,{\sec ^{ - 1}}$
So, option (B) is correct.
Now, using formula of linear velocity we have, $v = r\omega $ where $r$ is length of second-hand and it’s given as $r = 1m = 100cm$ and we find $\omega = \dfrac{\pi }{{30}}rad{\sec ^{ - 1}}$ so,
$v = r\omega $
$\Rightarrow v = 100 \times \dfrac{\pi }{{30}}$
$\Rightarrow v = \dfrac{{10\pi }}{3}\,cm\,{\sec ^{ - 1}}$
So, option (A) is correct.
Now, using formula of average acceleration ${a_{average}} = \dfrac{{\Delta v}}{t}$ we have, at $t = 15\min $ since linear velocity is independent of time and has a constant magnitude so, $\Delta v = 0$
$ \Rightarrow {a_{average}} = 0$
So, option (C) is correct.
Now, using the formula of instantaneous acceleration we have, $a = {\omega ^2}r$ where,
$\omega = \dfrac{\pi }{{30}}rad{\sec ^{ - 1}}$ And $r = 1m = 100cm$ we get,
$\Rightarrow a = \dfrac{\pi }{{30}} \times \dfrac{\pi }{{30}} \times 100$
$\therefore a = \dfrac{{{\pi ^2}}}{9}\,cm\,{\sec ^{ - 2}}$
So, option (D) is correct
Hence, the correct options are A, B,C and D.
Note:It should be remembered that, all the second-hand minute-hand and hour-hands of the clock rotate in circular direction and the basic unit of conversions are $1m = 100cm$ a complete angle in two dimensional Cartesian plane is of ${360^0}$ which thus in units of radian is written as $2\pi radians$ Also, minute hand covers an angle of $2\pi radians$ in $3600$ seconds.
Recently Updated Pages
When people say No pun intended what does that mea class 8 english CBSE
Name the states which share their boundary with Indias class 9 social science CBSE
Give an account of the Northern Plains of India class 9 social science CBSE
Change the following sentences into negative and interrogative class 10 english CBSE
Advantages and disadvantages of science
10 examples of friction in our daily life
Trending doubts
Difference between Prokaryotic cell and Eukaryotic class 11 biology CBSE
Which are the Top 10 Largest Countries of the World?
Fill the blanks with the suitable prepositions 1 The class 9 english CBSE
Differentiate between homogeneous and heterogeneous class 12 chemistry CBSE
Difference Between Plant Cell and Animal Cell
10 examples of evaporation in daily life with explanations
Give 10 examples for herbs , shrubs , climbers , creepers
Write a letter to the principal requesting him to grant class 10 english CBSE
How do you graph the function fx 4x class 9 maths CBSE