Finding Tension in Elevator Acceleration: Physics Problem Help

  • Thread starter Thread starter JeffC
  • Start date Start date
AI Thread Summary
The discussion revolves around solving a physics problem involving an elevator's upward acceleration and the tension in a cord holding a 4.4 kg bundle. The user seeks guidance on how to approach the problem, specifically using kinematic equations and Newton's second law. Key formulas mentioned include s=ut+1/2at² for calculating acceleration and T-mg=ma for determining tension. The user expresses gratitude for the forum's assistance and notes that they found a successful method to solve the problem. Overall, the thread highlights the collaborative nature of seeking help in understanding physics concepts.
JeffC
Messages
2
Reaction score
0
I was doing my homework for my physics class, but now I am stuck at two questions and don't know what to do. :( And I don't know where to start. If someone can get me started and little tips on how-to-solve this question, that'd be awesome! :D

If someone can help me solve this problem, I'd be really greatful! :) And I am glad that I found such a wonderful forum.

Thank you. :)
------
An elevator starts from rest with a constant upward acceleration and moves 1min the first 1.9 s. A passenger in the elevator is holding a 4.4 kg bundle at the end of a vertical cord. The acceleration of gravity is 9.8 m=s2 :What is the tension in the cord as the elevator accelerates? Answer in units of N.
 
Last edited:
Physics news on Phys.org
Can you figure out how fast the elevator is accelerating?
 
Use
s=ut+\frac{1}{2}at^2 to find the constant upward acceleration,a.
Use Newton's 2nd Law to find the tension :
T-mg=ma
T=m(a+g)
Upward direction is choosen to be positive, downward direction to be negative.
 
Thank you both of you for answering the question. :)

I actually tried couple of approaches and I discovered Leong's method is the best one and did it. :)

Thanks again for the help!
 
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}...
Back
Top