WB JEE 2024 | Rotational Motion Question 3 | Physics

WB JEE 2024

MCQ (Single Correct Answer)

-0.25

WB JEE 2024 Physics - Rotational Motion Question 2 English

A small ball of mass m is suspended from the ceiling of a floor by a string of length $$\mathrm{L}$$. The ball moves along a horizontal circle with constant angular velocity $$\omega$$, as shown in the figure. The torque about the centre (O) of the horizontal circle is

$$\mathrm{mgL} \sin \theta$$

$$\mathrm{mg} \mathrm{L}$$

$$0$$

$$\mathrm{mg} \mathrm{L} \cos \theta$$

WB JEE 2024

MCQ (Single Correct Answer)

-0.25

A small sphere of mass m and radius r slides down the smooth surface of a large hemispherical bowl of radius R. If the sphere starts sliding from rest, the total kinetic energy of the sphere at the lowest point $$\mathrm{A}$$ of the bowl will be [given, moment of inertia of sphere $$=\frac{2}{5} \mathrm{mr}^2$$]

WB JEE 2024 Physics - Rotational Motion Question 3 English

$$\mathrm{mg}(\mathrm{R}-\mathrm{r})$$

$$\frac{7}{10} \mathrm{mg}(\mathrm{R}-\mathrm{r})$$

$$\frac{2}{7}$$ mg $$(\mathrm{R}-\mathrm{r})$$

$$\frac{10}{7} \mathrm{mg}(\mathrm{R}-\mathrm{r})$$

WB JEE 2023

MCQ (Single Correct Answer)

-0.25

A mouse of mass m jumps on the outside edge of a rotating ceiling fan of moment of inertia I and radius R. The fractional loss of angular velocity of the fan as a result is,

$$\frac{m R^{2}}{I+m R^{2}}$$

$$\frac{I}{I+m R^{2}}$$

$$\frac{I-m R^{2}}{I}$$

$$\frac{I-m R^{2}}{I+m R^{2}}$$

WB JEE 2021

MCQ (Single Correct Answer)

-0.5

A uniform rod of length L pivoted at one end P is freely rotated in a horizontal plane with an angular velocity $$\omega$$ about a vertical axis passing through P. If the temperature of the system is increased by $$\Delta$$T, angular velocity becomes $${\omega \over 2}$$. If coefficient of linear expansion of the rod is $$\alpha$$($$\alpha$$ << 1), then $$\Delta$$T will be

$${1 \over \alpha }$$

$${1 \over 2\alpha }$$

$${1 \over 4\alpha }$$

$$\alpha$$

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