Asked by Haley
A 59 g particle is moving to the left at 29 m/s. How much net work must be done on the particle to cause it to move to the right at 38 m/s?
.....i have tried two different ways and gotten the wrong answer.
Kinetic Energy = 0.5 * Mass * (Change in Velocity)^2.
Change in Velocity here is 29+38=67m/s
Convert the Mass to kilograms: 0.059 kg
0.5 * 0.059 *67^2 = 132J
...then
Work is the change in kinetic energy. Since the particle of mass 64 (kilograms, pounds, whatever) is moving to the left at 27 (m/s, mph, whatever), you want to find how much work is require to completely change the particle's direction, and add velocity the other way. The change in velocity will NOT be 38-27, because that would simply be an increase of velocity in the direction it is current heading. Instead, the change in velocity will be 27 + 38, so 65. You have to overcome the velocity to the left, then add velocity to the right. Here's what you can do:
Work = KEf - KEo
KE = (1/2)mV^2
KEleft = (1/2)(64)(27)^2 = how much energy the particle has going left
KEstop = (1/2)(64)(0)^2 = how much energy when the particle is stopped
KEright = (1/2)(64)(38)^2 = how much energy the particle has going to the right
KEleft - KEstop = work to stop particle
KEstop - KEright = work to speed up the particle to the right (in the oppsite direction, but since energy is not a vector, you can remove the negative sign)
You can add the two numbers together, and you get your final answer
..i got 1.121 J
neither one of these answers are correct. Can anyone help me?
.....i have tried two different ways and gotten the wrong answer.
Kinetic Energy = 0.5 * Mass * (Change in Velocity)^2.
Change in Velocity here is 29+38=67m/s
Convert the Mass to kilograms: 0.059 kg
0.5 * 0.059 *67^2 = 132J
...then
Work is the change in kinetic energy. Since the particle of mass 64 (kilograms, pounds, whatever) is moving to the left at 27 (m/s, mph, whatever), you want to find how much work is require to completely change the particle's direction, and add velocity the other way. The change in velocity will NOT be 38-27, because that would simply be an increase of velocity in the direction it is current heading. Instead, the change in velocity will be 27 + 38, so 65. You have to overcome the velocity to the left, then add velocity to the right. Here's what you can do:
Work = KEf - KEo
KE = (1/2)mV^2
KEleft = (1/2)(64)(27)^2 = how much energy the particle has going left
KEstop = (1/2)(64)(0)^2 = how much energy when the particle is stopped
KEright = (1/2)(64)(38)^2 = how much energy the particle has going to the right
KEleft - KEstop = work to stop particle
KEstop - KEright = work to speed up the particle to the right (in the oppsite direction, but since energy is not a vector, you can remove the negative sign)
You can add the two numbers together, and you get your final answer
..i got 1.121 J
neither one of these answers are correct. Can anyone help me?
Answers
Answered by
MathMate
First, I do not know if the mass is 59 grams or 64 grams. You used each at different places. Computer exercises usually change the numbers when you make a second attempt. I don't know if that's what happened.
Secondly, you did not show your intermediate answers in the last two paragraphs, but they don't add up to 1.121 J like you said. I get 23.3J for stopping the particle (64 g), and about double that for pushing it to the right.
That makes a total of about 70 J.
Can you show your calculations?
Secondly, you did not show your intermediate answers in the last two paragraphs, but they don't add up to 1.121 J like you said. I get 23.3J for stopping the particle (64 g), and about double that for pushing it to the right.
That makes a total of about 70 J.
Can you show your calculations?
Answered by
Ryan
You would use the equation W=1/2(m)(v2^2-v1^2)
where m = mass, v2 = final velocity, and v1 is initial velocity
mass must be in kilograms
so it would be W=1/2(0.059)((38)^2-(29)^2)
and W=17.7885 J
where m = mass, v2 = final velocity, and v1 is initial velocity
mass must be in kilograms
so it would be W=1/2(0.059)((38)^2-(29)^2)
and W=17.7885 J
There are no AI answers yet. The ability to request AI answers is coming soon!
Submit Your Answer
We prioritize human answers over AI answers.
If you are human, and you can answer this question, please submit your answer.