WBJEE · Physics · Rotational Motion
If the Earth were to suddenly contract to \(\frac{1}{n}\) th of its present radius without any change in its mass, the duration of the new day will be nearly
- A \(24 / \mathrm{n} \mathrm{hr}\).
- B \(24 \mathrm{n} \mathrm{hr}\).
- C \(24 / \mathrm{n}^2 \mathrm{hr}\).
- D \(24 n^2 h r\).
Answer & Solution
Correct Answer
(C) \(24 / \mathrm{n}^2 \mathrm{hr}\).
Step-by-step Solution
Detailed explanation
Hints: \(\mathrm{I}_1 \omega_1=\mathrm{I}_2 \omega_2\)…
See the Complete Solution
Get step-by-step explanations for this and 2.5 Lakh+ more JEE, NEET & CET questions.
- Unlock all solutions
- Practice the full chapter
- Track accuracy across PYQs
4.8 rated on Google Play · 14,000+ reviews
More questions from Physics
- When a semiconducting device is connected in series with a battery and a resistance, a current is found to flow in the circuit. If however, the polarity of the battery is reversed, practically no current flows in the circuit. The device may beWBJEE 2017 Easy
-
A uniform rod AB of length 1m and mass 4kg is sliding along two mutually perpendicular frictionless walls OX and OY.
The velocity of the two ends of the rod A and B are 3 m/s and 4 m/s respectively, as shown in the figure. Then which
of the following statement(s) is/are correct?WBJEE 2024 Medium - A parent nucleus \(X\) undergoes \(\alpha\) -decay with a half-life of 75000 yrs. The daughter nucleus \(Y\) undergoes \(\beta\) -decay with a half-life of 9 months. In a particular sample, it is found that the rate of emission of \(\beta\) -particles is nearly constant (over several months) at \(10^{7} / \mathrm{h} .\) What will be the number of \(\alpha\) -particles emitted in an hour?WBJEE 2019 Medium
-
Consider the circuit shown. If all the cells have negligible internal resistance, what will be the current through the \(2 \Omega\) resistor when steady state is reached?WBJEE 2020 Hard - Two identical springs are connected to mass \(\mathrm{m}\) as shown \((\mathrm{k}=\) spring constant). If the period of the configuration in (a) is \(2 \mathrm{~S}\), the period of the configuration (b) isWBJEE 2011 Medium
- Which of the following quantity has the dimension of length?
(h is Planck's constant, m is the mass of electron and c is the velocity of light)WBJEE 2024 Hard
More PYQs from WBJEE
- Two charges \(+q\) and \(-q\) are placed at points \(A\) and \(B\) respectively which are at a distance \(2 L\) apart. \(C\) is the mid point of \(A\) and \(B\). The workdone in moving a charge \(+Q\) along the semicircle \(\operatorname{CSD}\left(W_1\right)\) and along the line \(\operatorname{CBD}\left(W_2\right)\) are
WBJEE 2025 Medium - The probability that a non-leap year selected at random will have 53 Sunday isWBJEE 2017 Medium
- A variable line passes through a fixed point \(\left(x_{1}, y_{1}\right)\) and meets the axes at \(A\) and \(B\). If the rectangle \(O A P B\) be completed, the locus of \(P\) is, \((O\) being the origin of the system of axes).WBJEE 2019 Medium
- Let \(f: R \rightarrow R\) be such that \(f\) is injective and \(f(x) f(y)=f(x+y) \quad\) for \(\quad\) all \(\quad x, y \in R, \quad\) if \(f(x), f(y)\) and \(f(z)\) are in \(G P,\) then \(x, y\) and \(z\) are inWBJEE 2013 Medium
- Two dice are tossed once. The probability of getting an even number at the first die or a total of 8 isWBJEE 2010 Easy
- Equivalent conductivity at infinite dilution for \(\quad\) sodium-potassium oxalate \(\left[\left(\mathrm{COO}^{-}\right)_{2} \mathrm{Na}^{+} \mathrm{K}^{+}\right]\) will be [given molar
conductivities of oxalate, \(\mathrm{K}^{+}\) and \(\mathrm{Na}^{+}\) ions at infinite dilution are \(148.2, \quad 50.1,\) \(73.5 \mathrm{S} \mathrm{cm}^{2} \mathrm{mol}^{-1}\) respectively \(]\)WBJEE 2013 Medium