Calculating tensions in ropes suspending an onject

AI Thread Summary
A 20 kg mass is suspended from a ceiling by two ropes at angles of 30° and 45°. The gravitational force acting on the mass is calculated as 196 N. The discussion highlights the need to consider both the y and x components of the tensions in the ropes to establish equilibrium. The initial approach focused only on the y components, which is insufficient for solving the problem. Incorporating the x components will provide the necessary equations to find the tensions in both ropes.
novae
Messages
15
Reaction score
1

Homework Statement


A mass of 20 kg is suspended from a ceiling by two lengths of rope that make angles of 30° and 45° with the ceiling . Determine the tension in each of the strings.

2.Relevant equations

Fg= mg

The Attempt at a Solution


Fg= 20 x 9.8 = 196 N

∑F= fnet=ma
Fg-FTtotal= 0
196= FTtotal
196= FT1y+ FT2y (y components of each of the tensions)
196= (cos60)(FT1) + (cos45)(FT2)
I think I'm doing something wrong and I don't knownwhat. In the textbook, instead of using the y components of the tensions, they just use the tensions, which doesn't make sense to me because it's the y components of the tensions that give the equilibrant force to Fg.
 
Physics news on Phys.org
What you're doing is fine, but don't forget the x-components. That will give you the second equation that you need to solve for your two unknowns.
 
  • Like
Likes novae
Doc Al said:
What you're doing is fine, but don't forget the x-components. That will give you the second equation that you need to solve for your two unknowns.
Ohhhhh right! I forgot about that! And then it's substitution and stuff from there, thank you!
 
Thread 'Voltmeter readings for this circuit with switches'
TL;DR Summary: I would like to know the voltmeter readings on the two resistors separately in the picture in the following cases , When one of the keys is closed When both of them are opened (Knowing that the battery has negligible internal resistance) My thoughts for the first case , one of them must be 12 volt while the other is 0 The second case we'll I think both voltmeter readings should be 12 volt since they are both parallel to the battery and they involve the key within what the...
Thread 'Trying to understand the logic behind adding vectors with an angle between them'
My initial calculation was to subtract V1 from V2 to show that from the perspective of the second aircraft the first one is -300km/h. So i checked with ChatGPT and it said I cant just subtract them because I have an angle between them. So I dont understand the reasoning of it. Like why should a velocity be dependent on an angle? I was thinking about how it would look like if the planes where parallel to each other, and then how it look like if one is turning away and I dont see it. Since...
Back
Top