Physics Chapter 3 Entry test MCQs
26. A body moves in a circle with increasing angular velocity. At time t= 6sec, the angular velocity is 27rad/s. What is the radius of circle made by the body where linear velocity is 81cm / (s’)
a. 3cm
b. 6cm
c. 7cm
d. 9cm
27. A wheel of radius 1 m covers an angular displacement of 180. Its linear displacement is
a. π rad
b. 3.14 m
c. 0.157 m
d. 6.28 m
28. Linear velocity or tangential velocity of any particle moving in a circular path of radius 2 m with angular velocity 8 rads-¹ will be:
a. 4m s-¹
b. 16m s-¹
c. 6m s-¹
d. 10m s-¹
29. The linear and angular velocities of a particle moving about the center of a circle of radius r, are related by
30. If a car moves with a uniform speed of 2 m s-¹ in a circle of radius 0.4 m. Its angular speed is
a. 5 rad s-1
b. 4 rad s-1
c. 2.8m s-1
d. 1.6 rad s-1
31. A disc of radius R=20cm is rotating about its axis with an angular velocity ω=20rad-1 on a horizontal smooth surface. The linear speed of point C on disc is
a. 1 ms-1
b. 4 ms-1
c. 2 ms-1
d. 4 πms-1
32. The length of the second hand of watch is 1cm. The velocity vector of the tip is of the second hand is cm per second is
a. 2π
b. 2π/60
c. 2π/12×60
d. 2π/24×60
34. For a particle in uniform circular motion the relation a= rα of accelerations hold. The acceleration a:
a. is centripetal acceleration
b. is tangential acceleration
c. is radial acceleration
d. Both A and B
35. A point on the rim of a wheel 4m in diameter has a velocity of 1600cms-1 . The Angular velocity of wheel is
a. 2 rads-1
b. 4 rads-1
c. 6 rads-1
d. 8 rads-1
36. The Acceleration of motor car is 8m/s2 . if the diameter of wheel be 2m, its angular acceleration will be.
a. 8 rad/s2
b. 10 m/s2
c. 16 rad/s2
d. 10 rad/s2
37. when a wheel 1m in diameter makes 30rev/mint, the linear speed of point on its rim in ms-1 is
a. 2π
b. π/2
c. 3π
d. 4π
38. A body is moving in a circular path with constant speed. The magnitude of tangential and centripetal acceleration are:
39. Work done due to centripetal force for circular motion will be:
a. Maximum
b. Reduced
c. Zero
d. Half
40. A 500 kg car takes a round turn of radius 50 m with a velocity of 36 km/hr. The centripetal force is
a. 750 N
b. 250 N
c. 1200 N
d. 1000 N
41. A cycle wheel of radius 0.4 m completes one revolution in one second then the acceleration of a point on the cycle wheel will be
a. 0.4m /s2
b. 0.8m /s2
c. 0.4π2 m /s2
d. 1.6π2 m /s2
42. A stone of mass m tied to a string of length L is rotated in a circle with the other end of the string as the centre. The speed of the stone is v. If the string breaks, the stone will move
a. Along the tangent
b. Toward the centre of circle
c. Away from centre of circle
d. All of these
43. The mud flies off the tyre of a fast moving car in the direction
a. Tangent to the moving tyre
b. Parallel to the moving tyre
c. Anti-parallel to the moving tyre
d. None of these
44. The force required to bend the normally straight path of a particle into a circular path is called————–force.
a. Bending
b. Traveling
c. Centripetal
d. Centrifugal
45. Which of the following is the correct vector form of centripetal force?
46. A body rotates with uniform speed in a circle of radius r and takes time to complete one revolution. what are the magnitude of the angular velocity ω, the linear velocity v and acceleration a?
47. A particle revolves round a circular path with a constant speed. The acceleration of the particle is
a. Along the tangent
b. Along the circumference of the circle
c. Zero
d. Along the radius
48. A car is moving with high velocity when it has a turn. A force acts on it outwardly because of
a. Centrifugal force
b. Centripetal force
c. Gravitational force
d. All the above
49. A cyclist turns around a curve at 15 miles/hour. If he turns at double the speed, the tendency to overturn is
a. Unchanged
b. Quadrupled
c. Doubled
d. Halved
50. A body of mass 5 kg is moving in a circle of radius 1m with an angular velocity of 2 radian/sec. The centripetal force is
a. 30 N
b. 10 N
c. 40 N
d. 20 N