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chavic
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I'm in very desperate need of help on one of my homework assignments, I have been getting A's and B's on most of my work, but now I have this. I have been working for several hours without one single answer correct . Any help would be greatly appreciated.
I went to the professor for help, but he doesn't speak good English and he gets mad when students don't understand physics as well as he does.
A bead slides without friction around a loop-the-loop as shown in the figure below. The bead is released from a height h = 3.15R.
<img src="http://www.webassign.net/pse/p8-15.gif"> (if image doesn't work you can copy and past the url in your browser)
(a) What is the bead's speed (V) at point A? Answer in terms of R and g, the acceleration of gravity.
(b) How large is the normal force on the bead if its mass is 5.70 g? N (downward)
1. Relevant equations
?
1. The attempt at a solution
I know your supposed to attempt a solution before you receive help (i did on the other problems), but I have no idea of where to go with this, if someone could just point me in the right direction...
2. Homework Statement
Two objects, m1 = 4.00 kg and m2 = 3.00 kg, are connected by a light string passing over a light frictionless pulley as shown in the figure below. The object of mass 4.00 kg is released from rest, h = 3.50 m above the ground.
<img src="http://www.webassign.net/pse/p8-13alt.gif">
(a) Using the isolated system model, determine the speed of the 3.00 kg object just as the 4.00 kg object hits the ground.
(b) Find the maximum height to which the 3.00 kg object rises.
KEi+Ui=KEf+Uf
2. The attempt at a solution
KEi+Ui=KEf+Uf
0+m1gh=1/2m1v^2 +m2gy? (?this solution gives me two variables?)
plug in numbers and simplify
137=2v^2 +19.4y
solve for v
sqrt(68.5-14.7y)=V
It seems simply enough, but I don't know how to get around the two variables.
3. Homework Statement
A daredevil plans to bungee jump from a balloon 76.0 m above a carnival midway. He will use a uniform elastic cord, tied to a harness around his body, to stop his fall at a point 10.0 m above the ground. Model his body as a particle and the cord as having negligible mass and obeying Hooke's law. In a preliminary test, hanging at rest from a 5.00 m length of the cord, he finds that his body weight stretches it by 1.30 m. He will drop from rest at the point where the top end of a longer section of the cord is attached to the stationary balloon.
(a) What length of cord should he use?
(b) What maximum acceleration will he experience?
3. Relevant equations
F=-KX
Again I have a problem. I am solving both for the skydiver's mass and for K, two separate variables
F=-KX
m(9.8)=-K(1.3)?
4. Homework Statement
A 2.00 kg block is attached to a spring of force constant 455 N/m as in the figure below. The block is pulled 5.85 cm to the right of equilibrium and released from rest.
(a) Find the speed of the block as it passes through equilibrium if the horizontal surface is frictionless.
b) Find the speed of the block as it passes through equilibrium (for the first time) if the coefficient of friction between block and surface is 0.350.
4. Relevant equations
KE=1/2mv^2
Spring Potential energy: Us=1/2KX
?
4. The attempt at a solution
K=455
1/2(455)(.0585)=U
13.3088=U
U=KE
KE=1/2mv^2
13.3088=1/2mv^2
13.3088=.5(2)v^2
13.3088=v^2
sqrt(13.3088)=V
3.6481=V
This is wrong
5. Homework Statement
A 5.60 kg block is set into motion up an inclined plane with an initial speed of v0 = 8.00 m/s. The block comes to rest after traveling 3.00 m along the plane, which is inclined at an angle of 30.0° to the horizontal.
<img src="http://www.webassign.net/pse/p8-33alt.gif">
(a) For this motion, determine the change in the block's kinetic energy
(b) For this motion, determine the change in potential energy of the block-Earth system.
(c) Determine the frictional force exerted on the block (assumed to be constant).
(d) What is the coefficient of kinetic friction?
5. Relevant equations
5. The attempt at a solution
I gave up on the last two, sorry
6. Homework Statement
A 10.0 kg block is released from point A in the figure below. The track is frictionless except for the portion between points B and C, which has a length of 6.00 m. The block travels down the track, hits a spring of force constant 2300 N/m, and compresses the spring to 0.400 m from its equilibrium position before coming to rest momentarily. Determine the coefficient of kinetic friction between the block and the rough surface between B and C.
<img src="http://www.webassign.net/pse/p8-57.gif">
6. Relevant equations
6. The attempt at a solution
I went to the professor for help, but he doesn't speak good English and he gets mad when students don't understand physics as well as he does.
Homework Statement
A bead slides without friction around a loop-the-loop as shown in the figure below. The bead is released from a height h = 3.15R.
<img src="http://www.webassign.net/pse/p8-15.gif"> (if image doesn't work you can copy and past the url in your browser)
(a) What is the bead's speed (V) at point A? Answer in terms of R and g, the acceleration of gravity.
(b) How large is the normal force on the bead if its mass is 5.70 g? N (downward)
1. Relevant equations
?
1. The attempt at a solution
I know your supposed to attempt a solution before you receive help (i did on the other problems), but I have no idea of where to go with this, if someone could just point me in the right direction...
2. Homework Statement
Two objects, m1 = 4.00 kg and m2 = 3.00 kg, are connected by a light string passing over a light frictionless pulley as shown in the figure below. The object of mass 4.00 kg is released from rest, h = 3.50 m above the ground.
<img src="http://www.webassign.net/pse/p8-13alt.gif">
(a) Using the isolated system model, determine the speed of the 3.00 kg object just as the 4.00 kg object hits the ground.
(b) Find the maximum height to which the 3.00 kg object rises.
Homework Equations
KEi+Ui=KEf+Uf
2. The attempt at a solution
KEi+Ui=KEf+Uf
0+m1gh=1/2m1v^2 +m2gy? (?this solution gives me two variables?)
plug in numbers and simplify
137=2v^2 +19.4y
solve for v
sqrt(68.5-14.7y)=V
It seems simply enough, but I don't know how to get around the two variables.
3. Homework Statement
A daredevil plans to bungee jump from a balloon 76.0 m above a carnival midway. He will use a uniform elastic cord, tied to a harness around his body, to stop his fall at a point 10.0 m above the ground. Model his body as a particle and the cord as having negligible mass and obeying Hooke's law. In a preliminary test, hanging at rest from a 5.00 m length of the cord, he finds that his body weight stretches it by 1.30 m. He will drop from rest at the point where the top end of a longer section of the cord is attached to the stationary balloon.
(a) What length of cord should he use?
(b) What maximum acceleration will he experience?
3. Relevant equations
F=-KX
The Attempt at a Solution
Again I have a problem. I am solving both for the skydiver's mass and for K, two separate variables
F=-KX
m(9.8)=-K(1.3)?
4. Homework Statement
A 2.00 kg block is attached to a spring of force constant 455 N/m as in the figure below. The block is pulled 5.85 cm to the right of equilibrium and released from rest.
(a) Find the speed of the block as it passes through equilibrium if the horizontal surface is frictionless.
b) Find the speed of the block as it passes through equilibrium (for the first time) if the coefficient of friction between block and surface is 0.350.
4. Relevant equations
KE=1/2mv^2
Spring Potential energy: Us=1/2KX
?
4. The attempt at a solution
K=455
1/2(455)(.0585)=U
13.3088=U
U=KE
KE=1/2mv^2
13.3088=1/2mv^2
13.3088=.5(2)v^2
13.3088=v^2
sqrt(13.3088)=V
3.6481=V
This is wrong
5. Homework Statement
A 5.60 kg block is set into motion up an inclined plane with an initial speed of v0 = 8.00 m/s. The block comes to rest after traveling 3.00 m along the plane, which is inclined at an angle of 30.0° to the horizontal.
<img src="http://www.webassign.net/pse/p8-33alt.gif">
(a) For this motion, determine the change in the block's kinetic energy
(b) For this motion, determine the change in potential energy of the block-Earth system.
(c) Determine the frictional force exerted on the block (assumed to be constant).
(d) What is the coefficient of kinetic friction?
5. Relevant equations
5. The attempt at a solution
I gave up on the last two, sorry
6. Homework Statement
A 10.0 kg block is released from point A in the figure below. The track is frictionless except for the portion between points B and C, which has a length of 6.00 m. The block travels down the track, hits a spring of force constant 2300 N/m, and compresses the spring to 0.400 m from its equilibrium position before coming to rest momentarily. Determine the coefficient of kinetic friction between the block and the rough surface between B and C.
<img src="http://www.webassign.net/pse/p8-57.gif">
6. Relevant equations
6. The attempt at a solution
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