1. A block of mass M sits on a frictionless surface and is pushed, compressing a spring 0.1 meter. The spring constant is 200 newtons per meter.
What force is required to compress the spring 10 meters?
How can I find the force?
2. We know that when we see a velocity is negative, we know it’s a reverse in direction. Then how about when acceleration is negative, does it mean a reverse in direction or decelerating.
3. As an electron moves from the negative plate to the positive plate, its acceleration
1) decreases 2) increases 3) remains the same.
I know the speed is increasing, but how can I know the acceleration is constant or not?
Thank you for help.
QUOTE (mia6+Jun 24 2008, 02:12 PM)
3. As an electron moves from the negative plate to the positive plate, its acceleration
1) decreases 2) increases 3) remains the same.
I know the speed is increasing, but how can I know the acceleration is constant or not?
Heh, it's depending how it moving with acceleration or not, what speed doing it
Most textbooks for childs is like fighting with millhouses, lol.
If force always is the same then there is aceleration. And if force don't exist (push one time electron and it moving) then aceleration don't exist (0).
Aceleration can chage depending on changing of force.
childish question is childiesh
1) 200N/m * 10m = 2000N. Unless the exercice tells more subtleties.
2) Negative acceleration: negative speed getting a bigger absolute value, or positive speed getting a smaller absolute value. Both give a negative acceleration.
To go a bit beyond: there is no absolute reference to measure a speed, no objective "zero-speed". "Positive" speed also depends the direction of your ruler. So it's normal that accelerations work for both positive and negative speeds.
3) This would depend on the form of the plates!
But as somebody asks you, he probably ignores it, so in order to get a good mark, let's suppose that the plates are flat and parallel and big, so that the field is uniform between them, where the electron is.
Then, the force exerted by this field is uniform, and so is the acceleration - at least for moderate speeds, say, with less than 20,000V.
DavidD, you've missed an apportunity to show that you're actually able to answer these very questions.
2) Negative acceleration: negative speed getting a bigger absolute value, or positive speed getting a smaller absolute value. Both give a negative acceleration.
To go a bit beyond: there is no absolute reference to measure a speed, no objective "zero-speed". "Positive" speed also depends the direction of your ruler. So it's normal that accelerations work for both positive and negative speeds.
3) This would depend on the form of the plates!
But as somebody asks you, he probably ignores it, so in order to get a good mark, let's suppose that the plates are flat and parallel and big, so that the field is uniform between them, where the electron is.
Then, the force exerted by this field is uniform, and so is the acceleration - at least for moderate speeds, say, with less than 20,000V.
DavidD, you've missed an apportunity to show that you're actually able to answer these very questions.
QUOTE (DavidD+Jun 24 2008, 03:10 PM)
Heh, it's depending how it moving with acceleration or not, what speed doing it
Most textbooks for childs is like fighting with millhouses, lol.
If force always is the same then there is aceleration. And if force don't exist (push one time electron and it moving) then aceleration don't exist (0).
Aceleration can chage depending on changing of force.
childish question is childiesh
David Dumberthanshlt, you should horse-whipped with a chainsaw for posting your mindless/disgusting garbage in this thread.
Most textbooks for childs is like fighting with millhouses, lol.
If force always is the same then there is aceleration. And if force don't exist (push one time electron and it moving) then aceleration don't exist (0).
Aceleration can chage depending on changing of force.
childish question is childiesh
David Dumberthanshlt, you should horse-whipped with a chainsaw for posting your mindless/disgusting garbage in this thread.
QUOTE (Enthalpy+Jun 24 2008, 04:16 PM)
1) 200N/m * 10m = 2000N. Unless the exercice tells more subtleties.
2) Negative acceleration: negative speed getting a bigger absolute value, or positive speed getting a smaller absolute value. Both give a negative acceleration.
To go a bit beyond: there is no absolute reference to measure a speed, no objective "zero-speed". "Positive" speed also depends the direction of your ruler. So it's normal that accelerations work for both positive and negative speeds.
3) This would depend on the form of the plates!
But as somebody asks you, he probably ignores it, so in order to get a good mark, let's suppose that the plates are flat and parallel and big, so that the field is uniform between them, where the electron is.
Then, the force exerted by this field is uniform, and so is the acceleration - at least for moderate speeds, say, with less than 20,000V.
DavidD, you've missed an apportunity to show that you're actually able to answer these very questions.
Hi,thanks for help. but just one question: for the first question asking about the force, why it is 200 * 10=2000, not 200*0.1=20?
2) Negative acceleration: negative speed getting a bigger absolute value, or positive speed getting a smaller absolute value. Both give a negative acceleration.
To go a bit beyond: there is no absolute reference to measure a speed, no objective "zero-speed". "Positive" speed also depends the direction of your ruler. So it's normal that accelerations work for both positive and negative speeds.
3) This would depend on the form of the plates!
But as somebody asks you, he probably ignores it, so in order to get a good mark, let's suppose that the plates are flat and parallel and big, so that the field is uniform between them, where the electron is.
Then, the force exerted by this field is uniform, and so is the acceleration - at least for moderate speeds, say, with less than 20,000V.
DavidD, you've missed an apportunity to show that you're actually able to answer these very questions.
Hi,thanks for help. but just one question: for the first question asking about the force, why it is 200 * 10=2000, not 200*0.1=20?
QUOTE (mia6+Jun 24 2008, 07:17 PM)
Hi,thanks for help. but just one question: for the first question asking about the force, why it is 200 * 10=2000, not 200*0.1=20?
because he typed it wrong.
honestly, if you're having questions on the most basic physics concepts the night before your exam, you're probably not going to have a fun day tomorrow.
because he typed it wrong.
honestly, if you're having questions on the most basic physics concepts the night before your exam, you're probably not going to have a fun day tomorrow.
QUOTE (mia6+Jun 24 2008, 02:12 PM)
1. A block of mass M sits on a frictionless surface and is pushed, compressing a spring 0.1 meter. The spring constant is 200 newtons per meter.
What force is required to compress the spring 10 meters?
How can I find the force?
I can calculate for you M mass force. Force is M kg*10m/s^2=10*M Newtons. The spring constant is 200 newtons per meter. Thus mass must be 20 kg to have 200 N force and to compress 1 meter of spring. To compres 0.1 meter mass should be 2kg.
Maybe question is this:
"What MASS is required to compress the spring 10 meters?
How can I find the MASS?"
Then answer is need 200 kg mass body. or 2000 N force.
What force is required to compress the spring 10 meters?
How can I find the force?
I can calculate for you M mass force. Force is M kg*10m/s^2=10*M Newtons. The spring constant is 200 newtons per meter. Thus mass must be 20 kg to have 200 N force and to compress 1 meter of spring. To compres 0.1 meter mass should be 2kg.
Maybe question is this:
"What MASS is required to compress the spring 10 meters?
How can I find the MASS?"
Then answer is need 200 kg mass body. or 2000 N force.
QUOTE (mia6+Jun 25 2008, 12:17 AM)
Hi,thanks for help. but just one question: for the first question asking about the force, why it is 200 * 10=2000, not 200*0.1=20?
Because you are asked what force would be required to compress it 10m, not 0.1.
Look, you know how many Newtons each meter takes to compress (200) and how many meters you want to compress (10)
Because you are asked what force would be required to compress it 10m, not 0.1.
Look, you know how many Newtons each meter takes to compress (200) and how many meters you want to compress (10)
QUOTE (mia6+Jun 25 2008, 01:17 AM)
Hi,thanks for help. but just one question: for the first question asking about the force, why it is 200 * 10=2000, not 200*0.1=20?
The first sentence of the question is irrelevant to the answer. If the spring constant is x, then the force required to compress y metres is equal x*y N
So if x = 200N/m and y = 10m then 0.1m doesn't even enter the equation!
The first sentence of the question is irrelevant to the answer. If the spring constant is x, then the force required to compress y metres is equal x*y N
So if x = 200N/m and y = 10m then 0.1m doesn't even enter the equation!
QUOTE (DavidD+Jun 25 2008, 07:07 AM)
I can calculate for you M mass force. Force is M kg*10m/s^2=10*M Newtons. The spring constant is 200 newtons per meter. Thus mass must be 20 kg to have 200 N force and to compress 1 meter of spring. To compres 0.1 meter mass should be 2kg.
Maybe question is this:
"What MASS is required to compress the spring 10 meters?
How can I find the MASS?"
Then answer is need 200 kg mass body. or 2000 N force.
DavidD gets the right answer but he does it in a truly awful way. If I were you I'd ignore his posts as much as possible. Thats what I do
Let us know how you get on with you exam (and what exam it is come to think of it).
Maybe question is this:
"What MASS is required to compress the spring 10 meters?
How can I find the MASS?"
Then answer is need 200 kg mass body. or 2000 N force.
DavidD gets the right answer but he does it in a truly awful way. If I were you I'd ignore his posts as much as possible. Thats what I do
Let us know how you get on with you exam (and what exam it is come to think of it).
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