Can you me with Newtons 3rd Law

AI Thread Summary
To find the tension force and acceleration in a pulley system with two masses, start by identifying the net force acting on the system. For a frictionless pulley with a 4kg mass and a 3kg mass, the net force can be calculated as the difference in weight, resulting in a force of 10N. Using Newton's second law (F=ma), the total mass (7kg) allows you to determine the acceleration. The tension in the rope can be calculated using the formula for each mass, ensuring that the values are consistent. This approach clarifies the relationship between tension, acceleration, and the forces acting on the masses.
slobodan48
Messages
9
Reaction score
0
how do you find the Tension force,acceleration,magnitude.
Its those questions where you have pullys,boxes pushing each other...
I am really confused for the 3rd law
 
Physics news on Phys.org
slobodan48 said:
how do you find the Tension force,acceleration,magnitude.
Its those questions where you have pullys,boxes pushing each other...
I am really confused for the 3rd law

Do you have a specific example? I'd hate to just vapidly repeat the definition of the 3rd law, which you can easily find anywhere and everywhere...
 
Two masses are places in a frictionless pulley system.Solve for the acceleration and tension forces.
1st box is 4kg and the other is 3kg

well i know,
fnet=ma
fg=mg
ff=muFn
 
You could start by saying that there is a net, unbalanced force of 10N (For GCSE level thought - or you can do 9.81m/s/s, if you like), pulling one up and one down.
This is accelerating both the masses (7kg total), use your formula to find the acceleration.
The tension will be ml times (g + this acceleration) for the light mass and also mh times (g- this acceleration) for the heavy mass. Those two values should be the same, natch - as a check.
etc etc - you can put in the numbers
 

Thread 'Is calling fictitious forces "not real" just about terminology?'

Hi there, im studying nanoscience at the university in Basel. Today I looked at the topic of intertial and non-inertial reference frames and the existence of fictitious forces. I understand that you call forces real in physics if they appear in interplay. Meaning that a force is real when there is the "actio" partner to the "reactio" partner. If this condition is not satisfied the force is not real. I also understand that if you specifically look at non-inertial reference frames you can...
View full post »

Thread 'Inclined treadmills and Galilean Invariance'

This has been discussed many times on PF, and will likely come up again, so the video might come handy. Previous threads: https://www.physicsforums.com/threads/is-a-treadmill-incline-just-a-marketing-gimmick.937725/ https://www.physicsforums.com/threads/work-done-running-on-an-inclined-treadmill.927825/ https://www.physicsforums.com/threads/how-do-we-calculate-the-energy-we-used-to-do-something.1052162/
View full post »

Thread 'Derivation of Hamilton's Principle: Questions'

I have recently been really interested in the derivation of Hamiltons Principle. On my research I found that with the term ##m \cdot \frac{d}{dt} (\frac{dr}{dt} \cdot \delta r) = 0## (1) one may derivate ##\delta \int (T - V) dt = 0## (2). The derivation itself I understood quiet good, but what I don't understand is where the equation (1) came from, because in my research it was just given and not derived from anywhere. Does anybody know where (1) comes from or why from it the...
View full post »

Similar threads

B Newton's 3rd Law interactions with 2nd and 1st Law Partners
Replies
8
Views
2K
B Are frictional forces action forces or reaction forces?
Replies
14
Views
1K
Confused about Newton's 3rd law
Replies
22
Views
3K
Analysis of a deformable body and Newton's 3rd Law
Replies
31
Views
3K
B Newton's Third Law in space
Replies
20
Views
2K
I Extending Newton's laws -- Is the concept of force still defined?
Replies
35
Views
5K
I Stuck in understanding Newton's 3 laws
Replies
18
Views
2K
I Newton's Third Law: Action & Reaction Along the Line Connecting Two Objects
Replies
5
Views
1K
I 1st law of Newton as a special case of the 2nd law (historical aspect)
Replies
10
Views
3K
How Does Mass Influence the Reaction in Newton's 3rd Law of Motion?
Replies
9
Views
2K

Hot Threads

Recent Insights

Back
Top