Blog Log in Get Started Free

NEET Practice Questions (MCQs) with Answers & Solutions

Practice free NEET NEET multiple-choice questions online with instant answers and detailed explanations. No login required.

All Physics Chemistry Botany Zoology

Language English हिंदी

● ● ● ● ●

The magnitude of the impulse developed by a mass of 0.2 kg which changes its velocity from $5 \hat{i} - 3 \hat{j} + 7 \hat{k} m / s to 2 \hat{i} + 3 \hat{j} + \hat{k} m / s$ is

2.7 N-s

1.8 N-s

0.9 N-s

3.6 N-s

You've reached today's free limit of 20 questions. Log in to keep practising for free.

Explanation

$\begin{aligned} Impulse J = Δp & = m (v_{r} - v_{i}) \end{aligned} 0 .2 [(2 \hat{i} + 3 \hat{j} + \hat{k}) - (5 \hat{i} - 3 \hat{j} + 7 \hat{k})] = (- 0 .6 \hat{i} + 1 .2 \hat{j} - 1 .2 \hat{k}) ∴ J = \sqrt{(0 .6)^{2} + (1 .2)^{2} + (1 .2)^{2}} = 1 .8 N - s$

● ● ● ● ●

A round disc of the moment of inertia $l_{2}$ about its axis perpendicular to its plane and passing through its center is placed over another disc of the moment of inertial $l_{1}$ rotating with an angular velocity $ω$ about the same axis. The final angular velocity of the combination of discs is

$\frac{l_{2} ω}{l_{1} + l_{2}}$

$ω$

$\frac{l_{1} ω}{l_{1} + l_{2}}$

$\frac{(l_{1} + l_{2}) ω}{l_{1}}$

You've reached today's free limit of 20 questions. Log in to keep practising for free.

Explanation

According to the conservation of angular momentum

$∵ l_{1} ω_{1} = l_{2} ω_{2} \Rightarrow l_{1} ω = (l_{1} + l_{2}) ω_{2} \Rightarrow ω_{2} = \frac{l_{1} ω}{l_{1} + l_{2}}$

● ● ● ● ●

A solid sphere is rotating in free space. If the radius of the sphere is increased keeping mass same which one of the following will not be affected

Moment of inertia

Angular momentum

Angular velocity

Rotational kinetic energy

You've reached today's free limit of 20 questions. Log in to keep practising for free.

Explanation

Since no external torque acts on sphere, hence its total angular momentum remains constant.

● ● ● ● ●

A particle of mass 5 g is moving with a uniform speed of $3 \sqrt{2}$ cm/s in the x-y plane along the line y = $2 \sqrt{5}$ cm. The magnitude of its angular momentum about the origin in $g - {cm}^{2} / s$ is

$30 \sqrt{2}$

$30 \sqrt{10}$

You've reached today's free limit of 20 questions. Log in to keep practising for free.

Explanation

The angular momentum of a particle about an axis is given by mvr sin(Î¸), where m is the mass, v is the speed, r is the perpendicular distance from the axis, and Î¸ is the angle between v and r. For the given trajectory, r = 2âˆš5 cm and sin(Î¸) = 2/âˆš10. Substituting the values, we get L = 30âˆš10 g-cm^2/s.

● ● ● ● ●

Three-point masses, each of mass m are placed at the corners of an equilateral triangle of side a. The moment of inertia of this system ab5ut an axis along one Side of the triangle is

$3 {ma}^{2}$

${ma}^{2}$

${ma}^{2} \frac{3}{4}$

$\frac{3}{2} {ma}^{2}$

You've reached today's free limit of 20 questions. Log in to keep practising for free.

Explanation

As the mass are point masses. The M.I. of masses lying on-axis is zero.

$∴ M . I . of the third mass abour one side as axis = m \times (\frac{\sqrt{3}}{2} a) = \frac{3 {ma}^{2}}{4}$

● ● ● ● ●

A closed tube partly filled with water lies in a horizontal plane. If the tube is rotated about perpendicular bisector, the moment of inertia of the system

increases

decreases

remains constant

depends on sense of rotation

You've reached today's free limit of 20 questions. Log in to keep practising for free.

Explanation

The mass tries to go away from the axis and, therefore, M.I. increases.

● ● ● ● ●

A disc is rotating With an angular speed of m. If a child sits on it, which of the following is conserved?

kinetic energy

potential energy

linear momentum

angular momentum

You've reached today's free limit of 20 questions. Log in to keep practising for free.

Explanation

According to the principle of conservation of angular momentum, when the child sits on the rotating disc, moment of inertia changes, so angular velocity also must change so as to keep angular momentum, as there is no torque acting on the system.

● ● ● ● ●

The torque of a force -6 $\hat{i}$ acting at a point r = 4 $\hat{j}$ about origin will bee

-24 $\hat{k}$

24 $\hat{k}$

24 $\hat{j}$

24 $\hat{i}$

You've reached today's free limit of 20 questions. Log in to keep practising for free.

Explanation

$τ = r \times F$

● ● ● ● ●

A particle moves in a force field given by $\vec{F} = \hat{r} F (r)$ , where r is the unit vector along with the position vector $\vec{r}$ , then which is true?

The torque acting on the particle is not zero

The torque acting on the particle produces an angular acceleration in it

The angular momentum of the particle is conserved

The angular momentum of the particle increases.

You've reached today's free limit of 20 questions. Log in to keep practising for free.

Explanation

$\begin{aligned} \vec{t} = \vec{r} \times \vec{F} & = \vec{r} \times \hat{r} F (r) = 0 \\ Therefore, \vec{t} & = \frac{\vec{dL}}{dt} = 0; \vec{L} = constant \end{aligned}$

● ● ● ● ●

The ratio of rotational and translatory kinetic energies of the sphere is

2/9

2/7

2/5

7/2

You've reached today's free limit of 20 questions. Log in to keep practising for free.

Explanation

$\frac{Rotational kinetic energy}{Translatory kinetic energy} = \frac{\frac{1}{2} {mv}^{2} \frac{K^{2}}{R^{2}}}{\frac{1}{2} {mv}^{2}} = \frac{K^{2}}{R^{2}} = \frac{2}{5}$

Ready to ace NEET?

Free access · No credit card required

Browse All Questions Create Free Account

Frequently Asked Questions

Yes. You can attempt every NEET question on this page for free without logging in, and check the correct answer with a detailed explanation instantly.

No account is required to attempt questions and view answers. A free account adds bookmarks, personal notes, and progress tracking.

The bank mixes NEET previous year questions (PYQs) with practice questions, each tagged with its exam appearances where applicable.