UTexas HW14: PV Diagrams #2

Dr. Winters said she would put up how to do it but this is my last question and i dont really wish to leave this blank so... can anyone that actually got the answer right explain how to get it...

UT HW10: #6

I did P=Po+rogh but it didn't work, I don't know what I'm doing wrong....and I also don't know what numbers I'm supposed to be plugging in: the oil or the water?

UT HW Extra Credit #39

I think this has to do with momentum, but I have no idea how to go about doing it

UTexas HW7 #17

I might know how to start it, but I am completely winging it. Can anybody help me?

UT HW7: #15

I got 14, and I thought this was an energy problem, so I did mgh=1/2mv^2, but it didn't work. What should I be doing?

uTexas HW7 #18

I got question 17, but I don't see how we're supposed to find the maximum compression without knowing the spring constant. Can anyone help me out?

Texas HW6B #s 19 and 20

I am very confused on how to even set up these ones. I need some help desperately.

UT HW6B: #9

No idea how to even start this or go about doing it....

Last Question: 15 on the UT HW6

Ok. So, I got the first answer and I know I got the height right since the 1st part is correct. But I don't know how to set up an equation for this one. This is my last question for the hw.

UT HW6 #s 18 and 19

I am confused on how to do these ones. I got 17 but I am not sure how to use it in the next questions.

UT HW6 #12 and 13

I am really stumped on these. Can anybody help me out?

UT HW6 #16

I tried using the equation U1=K2, or mgh=1/2kx^2, but it didn't work. I'm confused about how to find the height and where the angle comes into the problem, and how to figure it out?

UT HW #18

I am very confused on how to do number 18. I already took 5 tries! HELP! This is my last one!

HW5 Number 7

Number 7 is really throwing me off, can anybody help?

UT HW5 #6

I got the first answer, but I am confused on how to get the second part asking for the speed of the 2nd sled. Can  any body help me with this?

UT HW5 # 17 and 18

I got number 16 but i dont know how to do number 17 and 18. Help ?

UT5 #8

I tried to find the acceleration by doing F=ma, a=F/m by finding the force in the perpendicular direction, and using the mass that was given. What am I doing wrong and how can I get the answer

UT HW5 #5 ?

Did anyone start this question...me and Vicky are working on it and are a little confused on how to set it up.

HW5 Question 14/15

has anybody worked through this problem yet and can have any suggestions about the best way to go about it?

MP1 extra credit opportunity

For +2 HW points for the 1st marking period:
Attend a talk at 5:30 on Tuesday Oct 4 at the Simon Center at Stony Brook University. Say hello to Dr. Winters to get credit for being there!

Brian Greene (a famous physicist) will be giving a general talk to the public called "Reaching for Einstein's Dreams". He is a good speaker and "high school students ... are especially encouraged to attend".

A link to the information is here: http://scgp.stonybrook.edu/archives/1735

If you go, get there early so you can find the place, and somewhere to park. If you can't go, don't panic. There will be other extra credit opportunities.

UTexas HW4 #s 1, 5 and 15.

I thought I knew how to set these up by looking at some of the other posts and our notes, but I couldn't get an answer. Can anybody help me with these?

UT HW 4 #7

I've used three tries on this one already and I have no clue why any of them are wrong. I drew an upward force equivalent to the light fixture and used the SOH formula. Does anybody know what am I doing wrong?

UT HW4 Tension problems

I'm kind of confused with the problems relating to tension of wires. How do you find the tension with the angles? I kind of remember the problem in class with the monkey hanging from the vines but I don't remember how to set it up. Can anybody help?

Question 7

I think I know the answer to this already, but am I looking for the force in each wire, or the total force between the two?

# 16 and 17

I am trying to figure out how to set this problem up. I know its similar to # 7 but i am confused because I don't know how to do it since the to two cables have different angles.

HW4 #5

I found all my components: xo=0, x=51.7, vo=0, and a= 9.8. First, I used to v^2 formula to find v, but that did not work. Then I found a using N=ma formula. I took the acceleration from that formula and plugged it into the v^2 formula, and that answer was also wrong. Does anyone have any ideas what I'm doing wrong?

UT #10

I got the acceleration for #9, but i can't figure out how to solve for tension. help please.

#8

Dear Dr.

I need help with eight because I have used 6/7 tries. Please help me.

Tension problems and problem 6

My first question is what is tension actually requiring you to find in the problem because a decent amount of the question ask you to find tension and for question 6, I drew a triangle with fgcostheta and fgsintheta but i cant figure out fg because i dont have the mass and i thought with this problem you were supposed to use cos and sin so im confused in how to go about this problem.

# 20

Q: A girl coasts down a hill on a sled, reaching

a level surface at the bottom with a speed

of 6.7 m/s. The coefficient of kinetic friction

between runners and snow is 0.048, and the

girl and sled together weigh 615 N.

The acceleration of gravity is 9.8 m/s.

How far does the sled travel on the level

surface before coming to a rest?

Answer in units of m

For this problem, I started it just like any other force problem. I set up a diagram drawing all the forces acting on the girl while going down the sled. Normal force perpendicular to the surface, Fg going downwards which is 615N, and the Ff which is mew (subscript k) times N. Mew in this instance is .048 as indicated in the question.

I believe you have to find the acceleration before you plug it into a kinematic equation. So using the equation F=ma, I decided to find mass first by using Fg= mg. Fg= 615N and g=9.8. So I did 615/9.8 to get the mass of 62.75510204.

Then would I use Ff= mew (times) N to find F in F=ma? If so, what would N=? Would it be 615?

#9

How would you approach and set up #9 because the acceleration i got for my answer is wrong but when i plug it in for part ii of the question to find the tension, i get a correct answer.

# 8

For this problem, it states A 5 kg bucket of water is raised from a well

by a rope.

The acceleration of gravity is 9.8 m/s

2

.

If the upward acceleration of the bucket is

4.2 m/s

2

, find the force exerted by the rope

on the bucket.

a) First I calculated the force for the rope going upward using the formula f=ma. Since it gave acceleration and mass i multiplied (4.2 m/s^s) and (5 kg) to get a force of 21 upward.

b) To calculate the force downward i used Fg= mg. m= 5 kg and g=9.8. I multiplied the twoand got a Fg of 49.

c) I am stuck on where to go from there. Would I subtract the two to get a net force being my final answer?

UT HW4 #16

Numbe 16. Use Weight/sin(theta)

UT HW3 #17

I am very confused on how to set this one up. Can anybody help me if they are still there?

UT HW3 #11

Mike M. also asked how to get the angle for #11.

In #10 you got a total x component and a total y component. You can draw where that would take you (in what quadrant) and find the angle knowing that tanθ=y/x if your θ is measured from the x-axis. However, they want the angle measured from the +x axis, so if your vector is in quadrant 1 then your answer would be between 0 and 90 degrees. If your vector is in quadrant 2 then your answer would be between 90 and 180 degrees. If your vector is in quadrant 3 then your answer would be between -90 and -180 degrees (measured counter-clockwise from the +x direction), and if your vector is in quadrant 4 then your answer would be between 0 and -90 degrees.
Good luck.

UT HW3 #12

I dont really get how to set it up. any one know how

UT HW3 #6

For number 5, I got the horizontal component of the displacement correct. But for some reason I can't get the vertical component of the displacement. I did sin(18.3◦) x 38.4m and I got 12.0573m, and it said it was wrong. Whenever I redo the problem, I keep getting the same answer. Am I doing something wrong? 

UT HW3 #2

I got the first part right but i cant figure out the second part.. anyone know how to do this one?

.

nevermind.

UT HW2 #13

For UT #13, im confused on how to set it up. Anybody know?

UT HW2 #6

Can anybody tell me how to set up #6? I kind of understand that the acceleration is going in the other direction, but I don't know how to find the average.

UTexas HW2 #16

How do i calculate for the horizontal component?

UTexaz HW2 #19

For number 19 in the UTexas homework, I was able to find the vertical and horizontal velocities of the ball but im confused on how to find the final answer of by how much the ball will clear/miss the crossbar. Anybody know how to set this up?

UT HW1 #5

I'm just a little confused on how to set up the problem about how far a faster car has to travel to beat the slower car by x minutes. Anybody know how to set it up?