Alpha Question Bank for Medical: Physics>Chapter 4 - Kinematics>Exercise-2>Q 68

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Assertion : A particle moves in a straight line with constant acceleration. The average velocity of this particle cannot be zero in any time interval.

Reason : For a particle moving in straight line with variable acceleration, the average velocity in a time interval is $\frac{u + v}{2},$ where $u$ and $v$ are initial and final velocity of the particle in the given time interval.

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Important Questions on Kinematics

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Alpha Question Bank for Medical: Physics>Chapter 4 - Kinematics>Exercise-2>Q 69

Assertion : For a particle moving in a straight line, velocity (

v

in

{ms}^{- 1}

) of the particle-in terms of time (

t

in

\sec

) is given by,

v = t^{2} - 6 t + 8 .

Then the speed of the particle is minimum at

t = 2 \sec .

Reason : For a particle moving in a straight line the velocity

v

at any time

t

may be minimum or may be maximum when

\frac{d v}{d t} = 0 .

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Alpha Question Bank for Medical: Physics>Chapter 4 - Kinematics>Exercise-2>Q 70

Assertion : Retardation is directly opposite to the velocity.

Reason : Retardation is equal to the time rate of decrease of speed.

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Alpha Question Bank for Medical: Physics>Chapter 4 - Kinematics>Exercise-2>Q 72

Assertion : If separation between two particles does not change then their relative velocity, will be zero.

Reason : Relative velocity is the rate of change of velocity of one particle w.r.t. another.

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Alpha Question Bank for Medical: Physics>Chapter 4 - Kinematics>Exercise-2>Q 73

Assertion : If speed of two particles is increasing at the same rate then their relative velocity will be constant.

Reason : If the acceleration vector of the two particles is same then their relative acceleration will be non-zero.

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Alpha Question Bank for Medical: Physics>Chapter 4 - Kinematics>Exercise-3>Q 1

A particle moves in a circle of radius

5 c m

with constant speed and time period

0.2 π s .

The acceleration of the particle is

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Alpha Question Bank for Medical: Physics>Chapter 4 - Kinematics>Exercise-3>Q 2

The position vector of a particle

\vec{R}

as a function of time is given by

\vec{R} = 4 \sin (2 π t) \hat{i} + 4 \cos (2 π t) \hat{j}

, where

R

is in meters,

t

in seconds ;

\hat{i}

and

\hat{j}

denote unit vectors along

x

and

Y

directions, respectively. Which of the following statements is wrong for the motion of the particle?

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Alpha Question Bank for Medical: Physics>Chapter 4 - Kinematics>Exercise-3>Q 4

A missile is fired for maximum range with an initial velocity of

20 m / s

. If

g = 10 m / s^{2}

, the range of the missile is

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Alpha Question Bank for Medical: Physics>Chapter 4 - Kinematics>Exercise-3>Q 5

A projectile is fired at an angle of

45 °

with the horizontal. The elevation angle of the projectile at its highest point as seen from the point of projection is___