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?