Need help with a question on Newtons Law's of Motion.

  • Thread starter Thread starter nelone
  • Start date Start date
  • Tags Tags
    Motion Newtons
AI Thread Summary
To find the tension in the elevator cable, consider the forces acting on the elevator: the downward gravitational force and the upward tension. The total mass of the elevator and passengers is 800 kg, and the elevator accelerates upward at 1.0 m/s². Using Newton's second law (F = ma), the equation T - 800g = 800a can be set up, where g is the acceleration due to gravity. It's important to focus on the method of solving the problem rather than providing direct numerical answers to encourage learning.
nelone
Messages
6
Reaction score
0
An elevator is moving upward with an acceleration of 1.0 m/s2. The total mass of the elevator and the passengers is 800kg. I need to find the tension in the elevator cable assuming g=32ft/s2. Need help, beginner in physics. Thanks!
 
Physics news on Phys.org
Draw a free body diagram of the elevator and figure out the magnitude of the total force, applied by the cable, that is required to make it accelerate upwards at 1 m/s. That's the tension in the cable.

- Warren
 
nelone said:
An elevator is moving upward with an acceleration of 1.0 m/s2. The total mass of the elevator and the passengers is 800kg. I need to find the tension in the elevator cable assuming g=32ft/s2. Need help, beginner in physics. Thanks!

Forces acting downwards are : Gravity (800g)
Forces acting upwards are : Tension.

Resolving forces and acceleration:
F = ma
T - 800G = 800x1
T = 800 + 800G

I never ever work in feet and can't believe they've given it to you in the form ft/s^2, is this an age old textbook or something? Personally i don't know the feet to m conversion but if gravity is 9.8m/s/s.
T = 8640N
 
Thank you very much
 
KnowledgeIsPower:

Please refrain from giving actual numerical answers to homework problems. It is much more constructive pedagogically to explain the method for solving the problem, but leave the actual numerical solution to the student.

- Warren
 
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 »

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 »

Similar threads

Feynman's Lectures exercise about Newton's laws
Replies
13
Views
2K
Newton's law problem: Pushing 2 stacked blocks on a horizontal table
Replies
13
Views
3K
Mechanics: Elevator Accelerating Downward
Replies
10
Views
4K
Understanding Sign Conventions in Elevator Tension Problems
Replies
6
Views
3K
Find the acceleration of the system (2 blocks sliding on a table)
Replies
23
Views
2K
Having a hard time learning Newton's 2nd law
Replies
5
Views
2K
Rank forces according to magnitude: Newton's 2nd/3rd laws
Replies
5
Views
7K
Forces and Elevators: Free-Body Diagrams and Calculations
Replies
9
Views
6K
How do you know when k in Hooke's law is positive or negativ
Replies
2
Views
3K
Question about Projectile Motion: Throwing a Flower Pot from a Balcony
Replies
18
Views
1K

Hot Threads

Recent Insights

Back
Top