Understanding Rotational Motion Problems

  • Thread starter Thread starter darkys
  • Start date Start date
  • Tags Tags
    Homework
AI Thread Summary
The discussion focuses on solving rotational motion problems, specifically regarding a wheel's displacement and a bowling ball's kinetic energy and angular momentum. The first problem asks for the distance a point on a wheel travels as it accelerates, prompting a debate on whether to calculate angular or linear displacement. The second problem involves calculating the bowling ball's total kinetic energy and angular momentum, with a point raised about needing the radius for the latter. Participants clarify that the radius of a bowling ball is commonly known, although one contributor humorously admits to not being familiar with bowling. Overall, the conversation highlights common challenges in understanding rotational motion concepts.
darkys
Messages
25
Reaction score
0
I'm having some trouble with a few rotational motion problems.

One question says... A wheel 33 cm in diameter accelerates uniformly from 240 rpm to 360 rpm in 6.5 s. How far will a point on the edge of the wheel travel in this time.

Is this asking for the angular displacement or the linear displacement?

The next one says A bowling ball of mass 7.3 kg rolls without slipping down a lane at 3.3m/s. (a) calculate its total kinetic energy. (b) Calculate its angular momentum

I can see how to get the total kinetic energy i think, but how do i find the angular momentum if i don't have the radius or the angular velocity?

Any help would be appreciated
 
Physics news on Phys.org
1.There's no linear movement,therefore u should compute the length of the circle the point travels in that time.
2.As for the last,i may be wrong,but you need the radius...

Daniel.
 
The radius of a bowling ball is common knowledge and shouldn't need to be put into the problem. Virtually everybody knows that the radius of a bowling ball is 10.85 cm (plus or minus .05 cm).

Most people do know that, right? :rolleyes:

BTW, a 7.3 kg bowling ball isn't legal - it's about 44 grams too heavy. Check here for all you want to know about a bowling ball: http://www.bowl.com/downloads/pdf/USBCequipmanual2005_sectionIII.pdf"
 
Last edited by a moderator:
Nope,Bob,i never did and never will play bowling.:-p

Daniel.
 
Thread 'Variable mass system : water sprayed into a moving container'

Thread 'Variable mass system : water sprayed into a moving container'

Starting with the mass considerations #m(t)# is mass of water #M_{c}# mass of container and #M(t)# mass of total system $$M(t) = M_{C} + m(t)$$ $$\Rightarrow \frac{dM(t)}{dt} = \frac{dm(t)}{dt}$$ $$P_i = Mv + u \, dm$$ $$P_f = (M + dm)(v + dv)$$ $$\Delta P = M \, dv + (v - u) \, dm$$ $$F = \frac{dP}{dt} = M \frac{dv}{dt} + (v - u) \frac{dm}{dt}$$ $$F = u \frac{dm}{dt} = \rho A u^2$$ from conservation of momentum , the cannon recoils with the same force which it applies. $$\quad \frac{dm}{dt}...
View full post »

Similar threads

Angular Momentum Problem: Mouse walking on a rotating turntable
Replies
5
Views
1K
What's the source of increase in rotational energy of carousel?
Replies
9
Views
2K
Why is the direction of kinetic/static friction up a ramp?
Replies
7
Views
1K
Damped harmonic motion
Replies
3
Views
653
Kinetic Energy of a Cylinder Rolling Without Slipping
Replies
21
Views
4K
Problem in understanding angular momentum of a rigid body
Replies
10
Views
2K
Avg Power in a Rotational Energy/Work Problem
Replies
6
Views
1K
Mechanics: Two masses on a pulley causing two cylinders to accelerate
Replies
16
Views
2K
Using the angular momentum principle for 2 pucks
Replies
3
Views
2K
MIT 8.01: Unwinding Drum Problem
Replies
9
Views
2K

Hot Threads

Recent Insights

Back
Top