# Physics B problems hard hard

• 8parks11
In summary, the conversation discusses calculating tension in a cable supporting an elevator car and finding the minimum coefficient of friction between cartons and a truck bed. It also includes a question about the reading on a spring scale in different scenarios. The answer to the first question is correct for b) and c), while for a) the correct answer is just mg. For the second question, the correct answer for a) is 1 and for b) is 1.1.
8parks11
physics B problems :( hard hard

A single cable supports an 837-kg elevator car. What is the tension in the cable when the car is moving with a) constant speed, b) an upward acceleration of 3.21 m/s^2 and c) a downward acceleration of 3.21m/s^2

I'm not totally lost. Since the T is directed downward, I can derive from

F=ma
T+mg=ma
T=ma+mg (since g is negative)

so I thought T would be for
a)873(1)+837(9.8)
b) 873(3.21)+(873)(9.8)
c) 873(-3.21)+873(9.8)

next question: A truck loaded with heavy cartons is forced to stop suddenly with a deceleration of 5.0m/s^2. Calculate the minimum coefficient of frcition between the cartons and the truck bed given that the cartons do not slide.

I thought it would just be 5. is this correct?

and last but not least

http://img216.imageshack.us/img216/5...caleid1.th.jpg
(ignore the mass of the scale btw)

what will the spring scale S in the middle read when
a) m1=1kg m2=1kg
b) m1=1.2kg m2=1kg

I thought it would be 1 for a) but that's not the answer.
b), I thought it would be 1.1

i did 1/2(m1+m2) but I don't think this is right
thanks

thanks

Last edited by a moderator:
8parks11 said:
A single cable supports an 837-kg elevator car. What is the tension in the cable when the car is moving with a) constant speed, b) an upward acceleration of 3.21 m/s^2 and c) a downward acceleration of 3.21m/s^2

I'm not totally lost. Since the T is directed downward, I can derive from

F=ma
T+mg=ma
T=ma+mg (since g is negative)

so I thought T would be for
a)873(1)+837(9.8)
b) 873(3.21)+(873)(9.8)
c) 873(-3.21)+873(9.8)

a) If you're moving at a constant speed, then acceleration is 0, not 1.
b) and c) Correct.

so a) is just mg and b) is also correct?

what will the spring scale S in the middle read when
a) m1=1kg m2=1kg

ok for this, the answer is 1.. kg? anyways its 1 something..

b) m1=1.2kg m2=1kg

ok how do I do this one?
I have no idea how

ccan someone confirm that
b) 1.1?

## 1. What is the best approach to solving difficult Physics B problems?

The best approach to solving difficult Physics B problems is to break them down into smaller, manageable parts. Start by identifying the key concepts involved and then work through each step methodically. It may also be helpful to draw diagrams or use equations to visualize the problem.

## 2. How can I improve my problem-solving skills in Physics B?

Practice and persistence are key to improving problem-solving skills in Physics B. Make sure to thoroughly understand the foundational concepts and then challenge yourself with a variety of problems. Don't be afraid to seek help from teachers or peers if you get stuck.

## 3. What are some common mistakes to avoid in solving Physics B problems?

One common mistake in solving Physics B problems is not paying attention to units. Make sure to convert all units to the appropriate system and keep track of them throughout the problem. Another mistake is rushing through the problem without fully understanding the concepts involved. Take your time and double-check your work to avoid errors.

## 4. How can I stay motivated when facing challenging Physics B problems?

It can be easy to get discouraged when faced with difficult Physics B problems, but remember that every problem you solve is an opportunity to learn and improve. You can also try breaking the problem down into smaller parts or taking a short break to clear your mind before returning to it with a fresh perspective.

## 5. Are there any resources available to help with Physics B problems?

Yes, there are many resources available to help with Physics B problems. Your textbook, class notes, and online tutorials can provide helpful explanations and practice problems. You can also attend study groups or seek help from a tutor or teacher if needed.

• Introductory Physics Homework Help
Replies
19
Views
3K
• Introductory Physics Homework Help
Replies
4
Views
2K
• Introductory Physics Homework Help
Replies
7
Views
2K
• Introductory Physics Homework Help
Replies
2
Views
2K
• Introductory Physics Homework Help
Replies
4
Views
9K
• Introductory Physics Homework Help
Replies
1
Views
888
• Introductory Physics Homework Help
Replies
6
Views
3K
• Introductory Physics Homework Help
Replies
7
Views
16K
• Introductory Physics Homework Help
Replies
1
Views
6K
• Introductory Physics Homework Help
Replies
1
Views
4K