Solving Angular Velocity Homework: Mass, Friction & Work

AI Thread Summary
The discussion revolves around a physics homework problem involving a puck in uniform circular motion on a frictionless table. The student is tasked with calculating the work done when the string is pulled down by 0.5 meters while maintaining a fixed radius of 0.8 meters. Key equations mentioned include the conservation of kinetic energy and the moment of inertia of the puck. The student struggles to determine the final angular velocity after the string is pulled. Suggestions include using the conservation of angular momentum to solve for the unknowns.
superaznnerd
Messages
59
Reaction score
0

Homework Statement


a small puck of mass .5kg is executing Uniform constant motion on a friction free horizontal table. The angular frequency of the puck is 10 sec-1 (counter clockwise) and the radius of the circular motion is .8m. the radius stays fixed as the student holds the string in place. he now pulls the string down .5 m and holds it again in place. what work did he do?


Homework Equations



KE(original)+ W = KE (final)
inertia of hockey puck on string = mr2
w = angular velocity
I = inertia

The Attempt at a Solution


KE(original)+ W = KE (final)
.5(I)w2 +W = KE final
.5 (.5)(.8)2(102) + W = KE final

now i have a problem solving for kinetic energy final...
KE final = .5(.5)(.5)2(102)(w2)
I can't figure out what w (angular velocity) is...
please help!
 
Physics news on Phys.org
Have you tried using the conservation of angular momentum?
 

Thread 'Struggling to understand the concept of this question (ice cube in water optics question)'

TL;DR Summary: I came across this question from a Sri Lankan A-level textbook. Question - An ice cube with a length of 10 cm is immersed in water at 0 °C. An observer observes the ice cube from the water, and it seems to be 7.75 cm long. If the refractive index of water is 4/3, find the height of the ice cube immersed in the water. I could not understand how the apparent height of the ice cube in the water depends on the height of the ice cube immersed in the water. Does anyone have an...
View full post »
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

System of two wheels of different sizes with an axle through their centers
2
Replies
67
Views
4K
Existential dilemma on angular velocity of a complex rigid body
Replies
25
Views
2K
Angular velocity of a bullet and two masses
Replies
12
Views
1K
Application of angular impulse to a problem
Replies
7
Views
2K
Using the angular momentum principle for 2 pucks
Replies
3
Views
2K
Maximum angular velocity of disc skidding across surface
Replies
1
Views
1K
What is the final angular velocity of each cylinder
Replies
1
Views
2K
Calculation of minimum angular velocity of a mass on a spinning plate
Replies
2
Views
2K
Year1 Mechanics (angular momentum)
Replies
9
Views
3K
Find velocities when a mass leaves a system of a rod with two masses
Replies
10
Views
2K

Hot Threads

Recent Insights

Back
Top