Tension In a String

Lori

1. Homework Statement 2. Homework Equations

Ook, so i'm really bad at physics, and i need someone to help explain why the answer is P=T+25 N
I thought it is P+T = 125
3. The Attempt at a Solution

Since the system is in constant velocity, then Fnet = 0 so that P + T + W = 0 Why isn't it P + T + 125 =0?

Attachments

• 55.7 KB Views: 491
Related Introductory Physics Homework Help News on Phys.org

jbriggs444

Homework Helper
Which direction does T pull on the 100 N weight?
Which direction does T pull on the 25 N weight?

Lori

Which direction does T pull on the 100 N weight?
Which direction does T pull on the 25 N weight?
T always pull away from the object. So, for the 100 N weight, Tension pulls downward and for 25N, the tension pulls upward

haruspex

Homework Helper
Gold Member
2018 Award
T always pull away from the object.
Yes.
So, for the 100 N weight, Tension pulls downward ...
Away from the 100N weight would be upwards, surely?

CWatters

Homework Helper
Gold Member
Perhaps draw a two free body diagrams, one for each mass.

• Lori

Lori

Perhaps draw a two free body diagrams, one for each mass.
Thanks , i drew it for the 25 N object and got that P = T+25! Attachments

• 7.3 KB Views: 84
Last edited by a moderator:
• jbriggs444

Lori

I have a question to add!
If i know that W = T for the second diagram , then I know that T = 100N right?

I can actually find P since P = 25+T , so that P=125

• CWatters

jbriggs444

Homework Helper
If i know that W = T for the second diagram , then I know that T = 100N right?

I can actually find P since P = 25+T , so that P=125
Right!

• Lori

"Tension In a String"

Physics Forums Values

We Value Quality
• Topics based on mainstream science
• Proper English grammar and spelling
We Value Civility
• Positive and compassionate attitudes
• Patience while debating
We Value Productivity
• Disciplined to remain on-topic
• Recognition of own weaknesses
• Solo and co-op problem solving