ABS COACHING CENTER
Physics Numerical’s For Practice
1. A 0.5 kg mass is rotated in a horizontal circle of radius 20 cm. Calculate the
centripetal force acting on it, if its angular speed of rotation is 0.6 rad/s.
[Ans: 0.036 N]
2. A particle performing UCM changes its angular velocity from 70 r.p.m. to 130 r.p.m.
in 18 s. Find the angular acceleration of the particle. [Ans: 0.349 rad/s2]
3. A fly wheel rotating at 420 r.p.m. slows down at a constant rate of 2 rad/s2. What time
is required to stop the fly wheel ? [Ans: 22 s]
4. A satellite revolves around the earth in a circular orbit of radius 7000 km. If its period
of revolution is 2 h, calculate its angular speed, linear speed and centripetal
acceleration. [Ans: i. 8.72 × 10-4 rad/s , ii. 6.104 km/s , iii. 5.32 m/s2]
5. The earth moves round the sun in an almost circular orbit of radius 1.5 × 10 11 m with
constant angular speed. Calculate its
i. angular speed ii. linear speed iii. Centripetal acceleration
[Given: 1 year = 3.156 × 107 sec, Mass of earth = 5.98 × 1024 kg]
[Ans: i. 1.99 × 10-7 rad/s , ii. 2.985 × 104 m/s , iii. 5.941 × 10-3 m/s2]
6. A wheel of radius 2 metre is making 60 revolutions per minute. Calculate the angular
velocity of any point on the rim. Ans. 2 rad / s
7. Find the angular displacement of a particle moving on a circle with angular velocity
 2 / 3 rad / s in 15 s. Ans. 10 rad
8. What is the angular speed of the second hand of a clock? If the second hand is 10 cm
long, then find the linear speed of its tip.
Ans. i. 1.047 x 10-1 rad/s
ii. 1.047 x 10-2 m/s
9. A particle is revolving in a circle of radius 10 cm with linear speed of 20 m/s. Find
(i) its period of revolution and (ii) frequency
10. An object of mass 2 kg attached to wire of length 5 m is revolved in a horizontal
circle. If it makes 60 r.p.m. Find its
i. angular speed
ii. linear speed
iii. centripetal acceleration
iv. centripetal
force
Ans. i. 6.284 rad/s ii. 31.42 m/s iii. 197.44 m/s2
iv. 394.88 N
11. A string breaks a tension of 10 kg. wt. If the string is used to resolve a body of mass
12 g in a horizontal circle of radius 50 cm, what is the frequency of revolution and
linear speed with which the body can be revolved? [g = 9.8 m/s2]
Ans. 20.34 rev/s, 63.9 m/s
12. The tangential acceleration of the tip of a blade is 47.13 m/s2 and its centripetal
acceleration is 473.9 m/s2. Find the value of linear acceleration of the tip of the blade.
Ans. 4.762 x 102 m/s2
13. The tangential acceleration of a body is 29.48 m/s2 and its linear acceleration is 52.3
m/s2. Find its radial acceleration.
Ans. 43.1 m/s2.
14.An aircraft takes a turn along a circular path of radius 2000 metre. If the linear speed
of the aircraft is 500 m/s, find the angular speed and the time required by it to complete
half the circular path.
Ans. i. 0.25 rad/s. ii. 12.56 s