Does velocity from rotational Ek add to a total velocity of a body?

AI Thread Summary
The discussion centers on determining the final velocity of a ball rolling off an inclined roof, focusing on the contributions of translational and rotational kinetic energy. To find the ball's landing point, one must apply the conservation of energy principle, which includes both forms of kinetic energy. While the center of mass motion may seem to only involve translational kinetic energy, the correct calculation requires considering both translational and rotational kinetic energy. This approach resolves the confusion regarding the necessity of including rotational energy in the calculations. Ultimately, accurate application of conservation of energy is essential for determining the ball's final velocity.
rammer
Messages
22
Reaction score
0
If we have a ball rolling down from inclined roof that has bottom part at certain height about the ground. I want to know where does the ball land after it leaves the roof. So at this point potential energy is transferred to kinetic (rotational + translational).

My question is: What is the expression I derive an initial velocity from? Is it EK(transl) or EK(transl)+EK(rot)?

I think it should be only EK(transl), because I'm interested only in motion of a centre of mass, right?
BUT, exercises in my book always counts with EK(rot), so I'm pretty confused.

Can you please make it little more clear to me??
 
Physics news on Phys.org
To find the final velocity of the ball as it leaves the roof you must use conservation of energy. That includes all forms of mechanical energy, which in this case is both rotational and translational KE.

Even though all you care about is the translational speed of the ball, in order to correctly find that speed you must use conservation of energy properly.
 
thank you
 

Thread '1:1 versus 2:1 Mechanical Advantage debate'

The rope is tied into the person (the load of 200 pounds) and the rope goes up from the person to a fixed pulley and back down to his hands. He hauls the rope to suspend himself in the air. What is the mechanical advantage of the system? The person will indeed only have to lift half of his body weight (roughly 100 pounds) because he now lessened the load by that same amount. This APPEARS to be a 2:1 because he can hold himself with half the force, but my question is: is that mechanical...
View full post »

Thread 'Average velocity as a weighted mean'

Hello everyone, Consider the problem in which a car is told to travel at 30 km/h for L kilometers and then at 60 km/h for another L kilometers. Next, you are asked to determine the average speed. My question is: although we know that the average speed in this case is the harmonic mean of the two speeds, is it also possible to state that the average speed over this 2L-kilometer stretch can be obtained as a weighted average of the two speeds? Best regards, DaTario
View full post »

Thread 'Newton's first law?'

Some physics textbook writer told me that Newton's first law applies only on bodies that feel no interactions at all. He said that if a body is on rest or moves in constant velocity, there is no external force acting on it. But I have heard another form of the law that says the net force acting on a body must be zero. This means there is interactions involved after all. So which one is correct?
View full post »

Similar threads

B Static friction needed for rolling without slipping
Replies
4
Views
2K
B The physics of flywheel launchers (like tennis ball shooters)
2
Replies
60
Views
4K
Does a rotating rigid body has single angular velocity.
Replies
3
Views
2K
Is the rotational KE of a rigid body considered as internal energy?
Replies
30
Views
3K
KE of off-center impacts in rotating and translating rigid bodies
Replies
5
Views
1K
B Impulse and distance from the axis of rotation
Replies
9
Views
2K
Representation of Rotating and Translating Body
Replies
3
Views
1K
Critical Velocity in a roller coaster cart
Replies
1
Views
3K
I Solving Wheel Coming to a Stop: FBD, Friction & Hysteresis
Replies
22
Views
4K
Speed of objects rolling down slopes
Replies
3
Views
15K

Hot Threads

Recent Insights

Back
Top