The discussion centers on calculating the angular velocity of a bicycle wheel given a cyclist's speed of 30 km/hr and a wheel diameter of 0.70 meters. The correct angular velocity is determined to be 23.7 rad/sec. Participants clarify that the relationship between linear speed (v) and angular speed (ω) is expressed by the equation v = ωr, where r is the radius of the wheel. The conversion of speed from km/hr to m/s is also highlighted as a crucial step in the calculation.
PREREQUISITESStudents studying physics, particularly those focusing on kinematics and dynamics, as well as educators seeking to clarify concepts related to angular motion.
Welcome to Physics Forums.bionut said:Homework Statement
A cyclist is traveling at a speed of 30km/hr. If the diameter of the bike wheel is 0.70 meter, what is the angular velocity of the wheels in rad/sec?
Homework Equations
The Attempt at a Solution
Hi, I have racked my brain trying ot work this out, I know the answer is 23.7 rad/sec
(but I don't know hoe to get there ;-(!
All I could come up with is 0.83m/s=speed and r=0.07m
Almost, the definition of angular velocity (or speed) should be in your notes or textbook. Perhaps you could look it up.bionut said:okay, not sure if I am thinking is on the right track, but would the angular speed be in reference to revolutions/time period? Where 1 revolution - 2(pi)r?
You're looking for something that related linear speed to angular speed. See, for example, here: http://hyperphysics.phy-astr.gsu.edu/hbase/rotq.html#avelbionut said:okay, all it says is angular speed = angular distance / change in time
Not quite. 30 km/hr is 8.33... m/s. So, the equation you need isbionut said:Okay, thankyou for your help... but I am back to sqaure 1 lol... gawd !
okay if v=wr and s=2pi and the displacmeent is 2pi (6.8 rad) X 0.70 = 4.40, and v=30km/hr , is the tangential velcoity 0.83m/s