







A dot on a child's car wheel 
20190428 

From julia: A wheel of a child’s car revolves at 10 rpm. A painted dot on the circumference of the wheel is 12 cm from the centre of rotation of the wheel. How far does the dot travel in 5 s, to one decimal place? Answered by Penny Nom. 





Angular velocity 
20181205 

From Kolade: Krusty the Clown and Sideshow Bob have covered themselves in velcro, and shot themselves out of a large
cannon so that they stick to a huge rotating velcro wheel (don’t try this at home). As shown in Figure 1(a),
Krusty is now stuck to a point 3.00 m from the center of the wheel while Bob is stuck to another point 5.00 m
from the center. The wheel is rotating counterclockwise at 10.0 rpm. Conveniently a set of axes is suspended
just in front the wheel (Krusty asked for axes, like the ones you would use to chop wood, so that he and Bob
could chase each other with them in the usual wholesome entertainment he is known for. Unfortunately, the
set designer misunderstood.) The axes do not rotate with the wheel.
(a) Find Krusty’s and Bob’s angular velocities, in radians per second. Answered by Penny Nom. 





A rotating wheel 
20180824 

From Kay: A wheel with a radius of 7 inches is rotating at 4 revolutions per second. What is the
linear speed v, in feet per second? Answered by p. 





Revolutions per minute 
20141024 

From Edward: Hello; I have a 28.2 inch diameter tire; do not worry about engine RPM or gear ratios, please tell me what the RPM
of that tire is at 8 MPH and 64 MPH. Thank you.
Sincerely; Edward Answered by Penny Nom. 





Riding on a Ferris wheel 
20140321 

From Claire: A Ferris wheel has a radius of 72 feet and its center is 85 feet above the ground. At the top of the Ferris wheel, Sam is in the topmost car. If the Ferris wheel makes two complete revolutions per minute, how high above the ground will Sam be after 10 seconds? Answered by Penny Nom. 





A rolling wheel 
20090329 

From Jules: How far does a wheel of radius 2 feet roll along level ground in making
300 revolutions? Answered by Penny Nom. 





The speed of a tire in revolutions per minute 
20090328 

From Jules: Suppose that a tire on a car has an outer diameter of 2,5 feet. How many
revolutions per minute does that tire make when the car is travelling 60
miles per hour? (hint:first find the angular velocity in radians per minute.) Answered by Harley Weston. 





I need to rebuild a wagon wheel 
20071026 

From Pat: I need to rebuild a wagon wheel, the metal wheel rim is 41" diameter, inside the rim is a one and a half inch by one and a half inch wood wheel.
I thought I would glue up a hexagon from a 2x6 or 2x8 piece of wood and then draw and cut out the 41" diameter wood circle.
? what would work better the 2x6 or the 2x8 and what is the lenghth of the cuts needed in order to give me the 41' diameter I need. Answered by Harley Weston. 





Rotational energy needs 
20070829 

From will: how much energy in KW do i need to start and subsequently rotate a 4 ton fly wheel of 1 metre radius at 12 rpm? Answered by Stephen La Rocque. 





What angle does the tire turn in 60s? 
20070604 

From San: An automobile, travelling at 80km/h, is towing a trailer. The wheels of the trailer
are 40cm in diameter. Through what angle does the tire turn in 60second? Answered by Stephen La Rocque. 





Trig  Ferris wheel 
20070213 

From Anthony: A ferris wheel is 250 feet in diameter and revolves every 40 seconds when in motion. Your step up to seat on the wheel at the bottom 2 feet above the ground so you are sitting 4 feet above the ground to start. Derive the formula for the height of your seat at time (t). If I go three times around, how long is the ride in ditance traveled? Answered by Stephen La Rocque and Penny Nom. 





Spins of a roulette wheel 
20010302 

From Bob: Here's a problem I'm working on myself.....If you look at six consecutive spins of a roulette wheel, how many combinations of red and black are possible? I.E. BRRBRB, BBBBBR, BBRRRB......ETC..... Answered by Claude Tardif. 

