Physics Chapter 3 Entry test MCQs
Topic 3
Rotational and Circular motion
1. A girl attaches a rock to a string, which she then swings counter-clockwise in a horizontal circle. The string breaks at point P in the figure, which shows a bird’s-eye view (as seen from above). Which path (A-E) will the rock follow?
a. Path A
b. Path B
c. Path C
d. Path D
2. The net acceleration of a particle in circular motion is
a. Irregular
b. Towards the center
c. Circular in motion
d. Always along the radius
3. A stone tied to the end of string 80cm long is whirled in horizontal circle with a constant speed. If the stone makes 14 revolutions in 25 sec, what is the magnitude of acceleration of the stone?
a. 720cm /s2
b. 680cm /s2
c. 990cm /s2
d. 860cm /s2
4. Motion of the tip of second hand of the clock is an example for———-.
a. Motion in a plane with uniform velocity
b. Uniform circular motion
c. Motion in a plane with constant acceleration
d. Projectile motion
5. Calculate the angular speed of flywheel making 420 revolutions per minute.
a. 10/4200 rad/sec
b. 42300 rad/sec
c. 44 rad/sec
d. 1200 rad/sec
6. Find the magnitude of the centripetal acceleration of a particle on the tip of a fan blade of length 0.30 metre, rotation at 1200 rev/minute
a. 245m /s2
b. 40m /s2
c. 20m /s2
d. 4737.6m /s2
7. The racing cars of masses m1 and m2 are moving in circles of radii r1 and r2 respectively. Their speeds are such that each makes a complete circle in the same length of time. The ratio of the angular speed of the first car to that of the second car is
a. r1 : r2
b. m1: m2
c. m1r1 : m2 r2
d. 1:1
8. The ratio of angular speeds of minute hand and hour hand of a watch is
a. 1:12
b. 6:1
c. 1:6
d. 12:1
9. The angular velocity of a particle rotating in a circular orbit 100 times per minute is
a. 10.47 deg/s
b. 1.66 rad/s
c. 60 deg/s
d. 10.47 rad/s
10. Angular speed of a particle increases 2rads-1 to 4 rads-1 across any two diametrically opposite positions. Its angular acceleration will be?
a. 6/π rads-2
b. 6 rads-2
c. πrads-2
d. π/6(5rads-2)
11. Radian is a unit of angular displacement which can also be measured in degrees. How many radians are equal to one degree?
a. π/180
b. 180/π
c. π/57.3
d. 2π/180
12. If a rotating body is moving counter clockwise, direction of angular velocity will be
a. Along the axis of rotation
b. Along linear velocity
c. Away from center
d. Towards the center
13. The ratio of angular frequency and linear frequency is
a. 1/2π
b. 2π
c. π/2
d. π
14. A flywheel gains a speed of 540 rpm in 6 second. Its angular acceleration is
a. 9 t rad s-2
b. 3 π rad s-2
c. 12 π rad s-2
d. 6 π rad s-2
15. The angular speed of a fly wheel making 120 revolutions/minute is
a. 4π2 rad/s
b. 2π rad/s
c. π rad/ s
d. 4π rad/s
16. For positive angular displacement the rotation would be
a. Parallel
b. Clockwise
c. Perpendicular
d. Anti-clockwise
17. Ten seconds after an electric fan is turned on, the fan rotates at 300rev/min. Its average angular acceleration is
a. 3.14 rad/s2
b. 30 rad/s2
c. 500rev /s2
d. 30rev /s2
18. The angular speed in radian/hour for daily rotation of the earth is
a. π/6
b. 2π
c. π/12
d. 4π
19. The shaft of a motor rotates at a constant angular speed of 360rev/min. Angle turned through in 1 sec in radian is
a. 3π
b. π
c. 12π
d. 6π
20. The angular velocity of the minute hand of a clock is
a. 2π/3600 rads-1
b. 2π/60 rad s-1
c. π/3600 rads-1
d. π/24 rad s-1
21. If a wheel of radius r turns through an angle of 30°, then the distance through which any point on its rim moves is
a. π/30r
b. π/3r
c. π/180r
d. π/6r
22. A body moving along the circumference of a circle, completes two revolutions. If the radius of the circular path is r, total angular displacement covered is
a. zero
b. πr
c. 4π
d. 2πr
23. When a body moves in a circle, the angle between its velocity vec v and angular velocity overline ω is always
a. 360°
b. 0°
c. 90°
d. 180°
24. An object is moving along a circular path of radius 4m. What will be its angular displacement if it moves 14m on this circular path?
a. 3.5 radians
b. 5.5 radians
c. 4.5 radians
d. 5.0 radians
25. Which of the following gives the relationship between linear velocity and angular velocity?
a. v = rθ
b. v = rω
c. v = sθ
d. v =sω