• Support PF! Buy your school textbooks, materials and every day products via PF Here!

Calculate the work required to move the block

  • Thread starter AbbeyC172
  • Start date

kuruman

Science Advisor
Homework Helper
Insights Author
Gold Member
8,224
1,808
Friction is a horizontal force. I'm assuming friction would be the floor on block, floor on man?
Yes. Let's do first "floor on block". The relevant expression is Friction = Ffloor on block, x = μ Ffloor on block, y. Do you see how it works? So, what do you need to find the force of friction?
I'm really lost as to what I'm even trying to figure out now.
Please answer my last question in B, in post #23. Then you will see better what's going on.
 

haruspex

Science Advisor
Homework Helper
Insights Author
Gold Member
2018 Award
31,691
4,683
friction would be the floor on block, floor on man?
You need to distinguish between kinetic and static friction. Which of those describes the friction between the floor and the man?
The surfaces in static friction do not move relative to each other, so static friction does no work.
 

kuruman

Science Advisor
Homework Helper
Insights Author
Gold Member
8,224
1,808
For some reason, I feel this isn't right?
Work done on a system is done by forces external to the system. The system cannot do work on itself. In this case if the system is block, then one has to consider the works done by all the forces on the block and add them up. That's what I was trying to guide you to. Likewise, if the system is the man, then one has to consider the works done by all the forces on the man and add them up.
Work on box by the man: 20 (100) (1) = 2000 ft x lbs
Yes.
So work done by just the man on the box is 2000 and since the work done total is zero, work done by the system would have to be -2000 lbs?
Yes, if you you rephrase it as the work done on the man.
Thank you so much for your help earlier but I needed someone present to talk it through to because this is such a weak subject for me to grasp,
I hope you have better understanding of the subject now. Face to face tutoring can be very productive.
 
21
0
Work done on a system is done by forces external to the system. The system cannot do work on itself. In this case if the system is block, then one has to consider the works done by all the forces on the block and add them up. That's what I was trying to guide you to. Likewise, if the system is the man, then one has to consider the works done by all the forces on the man and add them up.

Yes.

Yes, if you you rephrase it as the work done on the man.

I hope you have better understanding of the subject now. Face to face tutoring can be very productive.

Thank you for all the help! I will let you know what my professor says when he grades the paper.
 

Want to reply to this thread?

"Calculate the work required to move the block" You must log in or register to reply here.

Related Threads for: Calculate the work required to move the block

Replies
1
Views
6K
Replies
11
Views
31K
Replies
5
Views
4K
  • Posted
Replies
4
Views
3K
  • Posted
Replies
1
Views
6K
  • Posted
Replies
6
Views
14K
Replies
20
Views
26K
Replies
14
Views
2K

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
Top