A particle moving in the xy -plane experiences a velocity dependent force F → = k υ y i ^ + υ x j ^ , where υ x and υ y are the x and y components of its velocity υ → . If a → is the acceleration of the particle, then which of the following statements is true for the particle ?

quantity υ → × a → is constant in time

F → arises due to a magnetic field

kinetic energy of particle is constant in time

quantity υ → . a → is constant in time

EASY

Earn 100

The strong nuclear force is charge independent.

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Important Questions on Physical World

EASY

Physics>Mechanics>Physical World>Fundamental Forces of Nature

Which of the following interactions is the weakest?

EASY

Physics>Mechanics>Physical World>Fundamental Forces of Nature

The ratio

(\frac{E}{W})

of relative strength of electromagnetic force

(E)

to weak nuclear force

(W)

is,

EASY

Physics>Mechanics>Physical World>Fundamental Forces of Nature

(A) Ratio of the relative strength of gravitational to weak force is nearly $10^{- 3}$
(B) Ratio of the relative strength of gravitational to weak force is less than $10^{- 3}$
(C) Ratio of the relative strength of strong nuclear to electromagnetic force is nearly $10^{2}$
(D) Ratio of the relative strength of strong nuclear to electromagnetic force is nearly $10^{- 2}$ .

Which of the following is true?

EASY

Physics>Mechanics>Physical World>Fundamental Forces of Nature

Which of the following forces have highest range?
(a) Gravitational force
(b) Weak Nuclear force
(c) Electromagnetic force
(d) Strong Nuclear force

MEDIUM

Physics>Mechanics>Physical World>Fundamental Forces of Nature

A shell of mass

20 g

is fired by a gun of mass

100 kg .

If the shell leaves the gun with a speed of

800 m / s,

the speed of recoil of the gun is

EASY

Physics>Mechanics>Physical World>Fundamental Forces of Nature

Which of the following represents fundamental forces of nature?

EASY

Physics>Mechanics>Physical World>Fundamental Forces of Nature

Match the columns I and II

	Column I		Column II
A	Stoke's law	I	Pressure and energy
B	Turbulence	II	Hydraulic lift
C	Bernoulli's Principle	III	Viscous drag
D	Pascal's law	IV	Reynold's number

The correct match is

MEDIUM

Physics>Mechanics>Physical World>Fundamental Forces of Nature

A particle moving in the

xy

-plane experiences a velocity dependent force

\vec{F} = k (υ_{y} \hat{i} + υ_{x} \hat{j})

, where

υ_{x}

and

υ_{y}

are the

x

and

y

components of its velocity

\vec{υ}

. If

\vec{a}

is the acceleration of the particle, then which of the following statements is true for the particle ?

HARD

Physics>Mechanics>Physical World>Fundamental Forces of Nature

The maximum and minimum distances of a comet from the sun are

1.4 \times 10^{12} m

and

7 \times 10^{10}

m .

If it's velocity nearest to the sun is

6 \times 10^{14} m / s,

what is its velocity in the farthest position? (Assume the comet to be spherical)

EASY

Physics>Mechanics>Physical World>Fundamental Forces of Nature

Which of the following statement is incorrect?

MEDIUM

Physics>Mechanics>Physical World>Fundamental Forces of Nature

A rocket is fired vertically from the earth with an acceleration of 2g, where g is the gravitational acceleration. On an inclined plane inside the rocket, making an angle

θ

with the horizontal, a point object of mass m is kept. The minimum coefficient of friction

μ_{m i n}

between the mass and the inclined surface such that the mass does not move is:

HARD

Physics>Mechanics>Physical World>Fundamental Forces of Nature

In a particle accelerator, a current of

500 μ A

is carried by a proton beam in which each proton has a speed of

3 \times 10^{7} m / s

. The cross-sectional area of the beam is

1.50 m m^{2} .

The charge density in this beam (in

C / m^{3})

is close to

HARD

Physics>Mechanics>Physical World>Fundamental Forces of Nature

A ball is thrown upward with an initial velocity

V_{0}

from the surface of the earth. The motion of the ball is affected by a drag force equal to

m γ v^{2}

(where

m

is mass of the ball,

v

is its instantaneous velocity and

γ

is a constant). Time taken by the ball to rise to its zenith is:

EASY

Physics>Mechanics>Physical World>Fundamental Forces of Nature

The Nobel laureate ABDUS SALAM is known for discovery of

MEDIUM

Physics>Mechanics>Physical World>Fundamental Forces of Nature

Two blocks

A

and

B

of masses

m_{A} = 1 k g

and

m_{B} = 3 k g

are kept on the table as shown in figure. The coefficients of friction between

A

and

B

0.2

and between

B

and the surface of the table is also

0.2 .

The maximum force

F

that can be applied on

B

horizontally, so that the block

A

does not slide over the block

B

is : [Take

g = 10 m / s^{2}

]

MEDIUM

Physics>Mechanics>Physical World>Fundamental Forces of Nature

The force on a body of mass

1 kg

(20 \hat{i} + 10 \hat{j}) N

. If it starts from rest, then the position of the body at time

t = 2 s,

HARD

Physics>Mechanics>Physical World>Fundamental Forces of Nature

A body of mass

m

is moving in a straight line with momentum

p

. Starting at time

t = 0

, a force

F = a t

acts in the same direction on the moving particle during time interval of

T

. So that its momentum changes from

p

2 p

. The value of

T

EASY

Physics>Mechanics>Physical World>Fundamental Forces of Nature

Which of the following is a possible final step in applying the scientific method?

HARD

Physics>Mechanics>Physical World>Fundamental Forces of Nature

A train is moving slowly at

2 m / s

next to a railway platform. A man,

1.5 m

tall, alights from the train such that his feet are fixed on the ground. Taking him to be a rigid body, the instantaneous angular velocity (in

rad / s

) is

EASY

Physics>Mechanics>Physical World>Fundamental Forces of Nature

Let

G, W, S

and

E

be relative strengths of gravitational, weak nuclear, strong nuclear and electromagnetic forces. Identify the correct option

The strong nuclear force is charge independent.

Important Questions on Physical World

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