Angular Momentum of Colliding Pucks: 80g & 120g Mass, 4cm & 6cm Radius

AI Thread Summary
The discussion centers on calculating the angular velocity of two colliding pucks, one with a mass of 80g and radius of 4cm, and the other with a mass of 120g and radius of 6cm. After a glancing collision, the pucks stick together and spin, prompting a question about the angular momentum of the sliding puck. It is clarified that while the sliding puck has zero angular momentum about its own center of mass, it does possess angular momentum relative to the center of mass of the combined system. The key to solving the problem lies in determining the velocity of the center of mass. Ultimately, the correct angular velocity after the collision is 9 rad/s, contrasting with the incorrect calculation of 19 rad/s.
vijay123
Messages
122
Reaction score
0
dear ppl,
a puck of mass 80g and radius 4cm slides along an air table at a speed of 1.5m/s. it makes a glancing collision with a second puck of radius 6cm and mass 120g. because their rims are coated with glue, the stick together and spin after the collison. find their angular velocity.

the ans is 9 rad/s but i keep getting 19 rad/s. my doubt is that does the puck that slides carry any angular momentum by itself? i think it doesn't have coz its sliding but i am not sure...thanks
 
Physics news on Phys.org
While the sliding puck has zero angular momentum about its center of mass, it certainly has angular momentum about the center of mass of the two puck system. (And it's the angular momentum of the system that remains the same.) Hint: What's the velocity of the center of mass?
 
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

Hockey Puck Collision--momentum problem
Replies
2
Views
4K
Moment of Inertia about the CoM
Replies
4
Views
3K
Angular Momentum; rod & disk inelastic collision
Replies
10
Views
5K
Conservaion of Angular Momentum and Center of Mass
Replies
3
Views
8K
Angular Momentum: Puck Spinning
Replies
6
Views
7K
Angular Momentum Question concerning a Merry Go Round
Replies
44
Views
6K
What is the angular momentum of the system after the collision?
Replies
1
Views
2K
What is the Angular Momentum of the System After a Collision?
Replies
2
Views
3K
2D Elastic collision of varying mass, velocities, and angles
Replies
29
Views
4K
Angular momentum of a thin spherical shell
Replies
4
Views
6K

Hot Threads

Recent Insights

Back
Top