Physics

1. Angular Speed
Question 1: 10 kg mass is moving in circular path of radius 5m, completes one round
in 4 seconds. Calculate the linear speed and angular speed of mass.
Solution:
m = 10kg, r = 5m and t = 4 seconds, V = ?
Linear speed, V = 2πrt = 2 x 3.14 x 54
V = 7.85 m/s
Now, ω = Vr = 7.855 = 1.57 rad. /s
Question 2: Calculate the angular speed of an hour hand.
Solution:
Angular distance = 2 π & T = 12 hours = 12 x 60 x 60 s = 43200 s (this is the time for
one complete circular motion)
Now, ω = 2πt = 2 x 3.1443200 = 1.45 x 10−4 rad. /s
Question 3: What is the angular speed of earth of rotation of earth on its axis?
Solution:
Angular distance = 2 π = 2 x 3.14 = 6.28 rad.
Time period (T) = 24 hours = 24 x 60 x 60 = 86400 s
Now, ω = 2πt = 6.886400 = 7.27 x 10−5 rad. /s
Question 4: A wheel of 0.60m in radius is moving with a speed of 10m/s. Find the
angular speed.
Solution:
r = 0.60m and V = 10m/s
Now, ω = Vr = 100.60 = 16.67 rad./s

2. Question 5: The angular speed of wheel is 88 rad./s. Calculate the number of
revolutions made by it in one second.
Solution:
ω = 88 rad./s
1 rad./s = (12π) rev. /s
88 rad./s = 88(2×227) rev./s = 14 rev/s.
Marie Rose Domingo
III- St. Ignatius of Loyola