CHAPTER 5 : Circular Motion

(1)               The rotational K.E of hoop is equal to the.

(a)     its translational K.E

(b)    half than its translational K.E

(c)     double than its translational K.E

(d)    four times than its translational K.E

(2)               A hoop and disc have same mass and radius. Their rotational K.E are related by an equation.

(a)     K.E_hoop  = K.E _disc

(b)    K.E_hoop  = 2K.E _disc

(c)     K.E_hoop  = 1/2K.E _disc

(d)    K.E_hoop  = 4K.E _disc

(3)               The critical speed of an artificial satellite is.

(a)     6 Kms^-1

(b)    8.1 Kms^-1

(c)     7.9 Kms^-1

(d)    8 ms^-1

(4)               Geo-stationary satellite completes one rotation around earth in.

(a)     3 hours

(b)    6 hours

(c)     12 hours

(d)    12 hours

(5)               Radius of geo-stationary orbit form center of earth is nearly.

(a)     42000 km

(b)    36000 km

(c)     24000 km

(d)    18000 km

(6)               According to Einstein, the gravity interaction is possible between.

(a)     material objects only

(b)    material objects and electromagnetic radiation only

(c)     electromagnetic radiations.

(d)    none of the above.

(7)               One radian is equal to.

(a)     67.3^o

(b)    57.3^o

(c)     87.3^o

(d)    60^o

(8)               The period of a circular motion is given by.

(a)     T = rV

(b)    T = ww

(c)     T = 2pw

(d)    T = 2p/w

(9)               The direction of linear velocity of body moving in a circle is.

(a)     along the axis of rotation

(b)    along the tangent

(c)     directed towards the center

(d)    directed away from the center

(10)           When a body moves in a circle, the angle between its linear velocity and angular velocity is always.

(a)     180^o

(b)    0 ^o

(c)     90 ^o

(d)    45 ^o

(11)           The circumference subtends an angle.

(a)     p radian

(b)    2p radian

(c)     p/2 radian

(d)    4p radian

(12)           The relation between linear and angular acceleration is.

(a)   =    x  

(b)   =    x  

(c)   =   x  

(d)   =    x  

(13)     When a body is whirled in a horizontal circle by means of a string the centripetal force is supplied by.

(a)    mass of a body

(b)   velocity of body

(c)    tension in the string

(d)   centripetal the string

(14)           Centripetal force performs .

(a)    maximum work

(b)   minimum work

(c)    negative work

(d)   no work

(15)    When a body moves in a circle of radius ‘r’ with linear speed ‘V’, its centripetal force is.

(a)     mV / r²

(b)    mV / r

(c)     mV² / r

(d)    mV² / r²

(16)   A stone is whirled in a vertical circle at the end of a string. When the stone is at the highest position the

          tension is the string is.

(a)     maximum

(b)    zero

(c)     equal to the weight of the stone

(d)    less than the weight of the stone

(17)           The span of broad jump depends upon.

(a)    mass of the jumper

(b)   height of jump

(c)    angle of projection

(d)   none

(18)           In case planets the necessary acceleration is provided by.

(a)    Gravitational force

(b)   Frictional force

(c)    Coulomb force

(d)   Centripetal force

(19)           If a car moves with a uniform speed of 2 ms^-2 in a circle of radius 0.4. its angular speed is.

(a)    4 rad.  s^-1

(b)   5 rad   s^-1

(c)    1.6 rad s^-1

(d)   2.8 rad s^-1

(20)           A body can have constant velocity when it follows a.

(a)    elliptical path

(b)   circular path

(c)    parabolic path

(d)   rectilinear path

(21)           A body moving along the circumference of a circle completes two revolutions. If the radius of the circular path is R, the ratio of displacement to the covered path will be.\

(a)    p R

(b)   2p R

(c)    zero

(d)   4p R.

(22)           The angular speed for daily rotation of earth in rad s^-1 is.

(a)    2 p

(b)    p

(c)    4p

(d)    7.3 x 10^-5 rad^-1

(23)           When a wheel, 1 m in diameter makes 30 rev min, the linear speed of point on its rim in ms^‑1 is.

(a)    2p

(b)    p/2

(c)    p

(d)    20p

(24)           A cyclist cycling around a circular racing track, skids because

(a)    the centripetal force upon him is less than limiting friction

(b)    the centripetal force upon him is greater than limiting friction

(c)    the centripetal force upon him is equal to the limiting friction

(d)    the friction between the tyres of the cycle and road vanishes

(25)           If a wheel of radius r turns through an angle of 30^o, then the distance through which any point on its rim moves is.

(a)    p/3 x r

(b)    p/6 x r

(c)    p/30 x r

(d)    p/180 x r

(26)           In angular motion, Newton’s second law of motion is.

(a)    F = ma

(b)    F = ∆p/∆t

(c)    i =  la

(d)    all of above

(27)           Angular speed of second’s hand of a watch in rad^-1 is.

(a)    p

(b)    p/2

(c)    p/30

(d)    p/180

(28)           The shaft of a motor rotates at a constant angular speed of 360rev/min.

Angle turned through in 1 sec in radian is.

(a)    p

(b)    3p

(c)    6p

(d)    12p

(29)           What is outward force acting on a mass of 10 kg when rotating at one end of an inelastic string 10m long at speed of 1m/s?

(a)    1N

(b)    10N

(c)    2N

(d)    100N

(30)           If we whirl a stone at the end of a string in the vertical circle, it is likely to break when the stone is .

(a)    at the highest point

(b)    at the lowest point

(c)    at any point during motion

(d)    at the point where gravity is not acting

(31)           A body moving along the circumference of a circle completes two revolutions. If the radius of the circular path is R, the ratio of displacement to the covered path will be ____________.

(a)    √R

(b)    2√R

(c)    zero

(d)    4√R

(32)           A man of weight W is standing on an elevator which is ascending with an acceleration a. The apparent weight of the man is.

(a)    mg

(b)    mg – ma

(c)    mg + ma

(d)    mg – ma

(33)           Which one of the following planets is closer to the sun?

(a)    Pluto

(b)    Venus

(c)    Mercury

(d)    Mars

(34)           The planet nearest to the earth is.

(a)    Venus

(b)    Mars

(c)    Uranus

(d)    Sun

(35)           A satellite moving round the earth constitutes.

(a)    An inertial frame of reference

(b)    Non inertial frame

(c)    Neither  inertial nor non inertial

(d)    Both inertial and non inertial

(36)           Minimum number of communication satellites required to cover the whole earth is

(a)    4

(b)    3

(c)    2

(d)    5

(37)           A body of 2 kg is suspended from the ceiling of an elevator moving up with an acceleration g. its apparent weight in the elevator will be

(a)    9.8 N

(b)    19.6 N

(c)    129.4 N

(d)    39.2 N

(38)           If a body of mass 10 kg is allowed to fall freely, its weight becomes.

(a)    zero

(b)    98N

(c)    9.8N

(d)    10N

(39)           How many days would be in a year if the distance between the earth and the sun were reduced to half of its present value (assuming circular orbit)?

(a)    365 days

(b)    730 days

(c)    329 days

(d)    129 days

(40)           When a body is moving along a circular, path, it covers a certain angle in a given internal of time. Such type of motion is.

(a)    vibratory motion

(b)    linear motion

(c)    rotatory motion

(d)    angular motion