- #1
Ignoramus
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Basically, I've missed a week straight of school due to a family illness, and I get back today to find that our normal physics teacher is sick, and we have a substitute. I was able to read a bit on my own and understand most of it, but these are some that have stumped me a bit.
I do not know if I'm allowed to post more than one question, but I have four. Please check out my method (make sure I am going in the right direction, or if I need help). Sorry in advance for my bad latex
Compare the linear and angular velocities of the moon around the Earth between 1912 and now if the average distance is 3.84x105km, average linear velocity is 3.68x103kph
and the distance from the moon to the Earth in 1912 was 3.56x105km, and the 2009 distance is 4.07x105km
(I don't even know if these are accurate numbers, but they're the ones I was given)
[tex]v_{T}= r\omega[/tex]
This was the only equation that seemed to pertain to the question. The thing I am confused about is finding the different variables for different dates
To find the angular velocities in the different years, I did
[tex]\frac{v_{T}}{r_{1912}}= \omega_{1912} }[/tex] for 1912 and I got 1.03x10-2kph
and
[tex]\frac{v_{T}}{r_{2009}}= \omega_{2009} }[/tex] for 2009 and I got 9.04x10-3kph
They seem like really small numbers...
For the linear velocities, I assumed that [tex]\frac{v_{Tavg}}{r_{avg}}=\omega_{avg}[/tex] and got 9.58x10-3kph
With the number from that, I plugged that into
[tex]v_{T1912}=r_{1912}\omega_{avg} [/tex] and got 3410.5kph
and
[tex]v_{T2009}=r_{2009}\omega_{avg} [/tex] and got 3899.1 kph
A ball with a radius of 2m and mass of 1x104kg rolls down an incline plane with an angular acceleration of 6.13rad/s2
What is the torque acting on the ball, and the linear/angular velocities at the bottom of the plane?
see below
I honestly have not tried this problem, and I do not know which equations to use. Seems to me, that I would need an angle of the inclined plane to even do anything with this problem, but there literally is none. If somebody could give me a hint, I have my paper and pencil ready to go, as well as a calculator.
A string has an 89N tensile strength. One end of a 1m piece of this string is tied to a 4.54kg toy car. The other end is attached to a ring slipped over a pole so that the car can rotate around it freely. Calculate the maximum angular speed of the car without breaking the string. How many revolutions does the car travel in 1 minute (friction neglected)?
[tex]F_{c}=mr\omega^{2}[/tex]
[tex]\omega=\frac{d\theta}{dt}[/tex]
Using the first equation, I solved for omega getting
[tex]\omega=\sqrt\frac{F_{c}}{mr}[/tex]
[tex]\omega=\sqrt\frac{89N}{4.54}[/tex]
Getting 4.42rad/s
I wasn't quite sure on the revolutions part, although it should be simple. I'm fairly sure I'm incorrect. I did
[tex]\omega=\frac{d\theta}{dt}[/tex] so (4.42)(60s)=revolutions, and I got 265.2
Seems like too much, so I converted it into radians, and got 4.63 which is in my opinion a more feasible answer, but I thought I was in radians already...
A 10m centrifuge can spin at a linear velocity of 17.3 m/s and brake to a stop in 80 seconds
a)What is the torque produced?
b)What is the centripetal acceleration?
c)What is the centripetal force an an 80kg astronaut?
torque, see below
[tex]a_{c}=\frac{v_{T}^{2}}{r}[/tex]
[tex]F_{c}=\frac{mv_{T}^{2}}{r}[/tex]
This is another one that I have not tried. I still feel like I'm not given enough information. How can I find the torque without a force (a mass to find the force). I can't use the 80kg astronaut, as far as I know, otherwise it would have been the first question asked.
For the others, it looks like I could just plug and chug into the equations.
Please and thank you!
I do not know if I'm allowed to post more than one question, but I have four. Please check out my method (make sure I am going in the right direction, or if I need help). Sorry in advance for my bad latex
Homework Statement
Compare the linear and angular velocities of the moon around the Earth between 1912 and now if the average distance is 3.84x105km, average linear velocity is 3.68x103kph
and the distance from the moon to the Earth in 1912 was 3.56x105km, and the 2009 distance is 4.07x105km
(I don't even know if these are accurate numbers, but they're the ones I was given)
Homework Equations
[tex]v_{T}= r\omega[/tex]
The Attempt at a Solution
This was the only equation that seemed to pertain to the question. The thing I am confused about is finding the different variables for different dates
To find the angular velocities in the different years, I did
[tex]\frac{v_{T}}{r_{1912}}= \omega_{1912} }[/tex] for 1912 and I got 1.03x10-2kph
and
[tex]\frac{v_{T}}{r_{2009}}= \omega_{2009} }[/tex] for 2009 and I got 9.04x10-3kph
They seem like really small numbers...
For the linear velocities, I assumed that [tex]\frac{v_{Tavg}}{r_{avg}}=\omega_{avg}[/tex] and got 9.58x10-3kph
With the number from that, I plugged that into
[tex]v_{T1912}=r_{1912}\omega_{avg} [/tex] and got 3410.5kph
and
[tex]v_{T2009}=r_{2009}\omega_{avg} [/tex] and got 3899.1 kph
Homework Statement
A ball with a radius of 2m and mass of 1x104kg rolls down an incline plane with an angular acceleration of 6.13rad/s2
What is the torque acting on the ball, and the linear/angular velocities at the bottom of the plane?
Homework Equations
see below
The Attempt at a Solution
I honestly have not tried this problem, and I do not know which equations to use. Seems to me, that I would need an angle of the inclined plane to even do anything with this problem, but there literally is none. If somebody could give me a hint, I have my paper and pencil ready to go, as well as a calculator.
Homework Statement
A string has an 89N tensile strength. One end of a 1m piece of this string is tied to a 4.54kg toy car. The other end is attached to a ring slipped over a pole so that the car can rotate around it freely. Calculate the maximum angular speed of the car without breaking the string. How many revolutions does the car travel in 1 minute (friction neglected)?
Homework Equations
[tex]F_{c}=mr\omega^{2}[/tex]
[tex]\omega=\frac{d\theta}{dt}[/tex]
The Attempt at a Solution
Using the first equation, I solved for omega getting
[tex]\omega=\sqrt\frac{F_{c}}{mr}[/tex]
[tex]\omega=\sqrt\frac{89N}{4.54}[/tex]
Getting 4.42rad/s
I wasn't quite sure on the revolutions part, although it should be simple. I'm fairly sure I'm incorrect. I did
[tex]\omega=\frac{d\theta}{dt}[/tex] so (4.42)(60s)=revolutions, and I got 265.2
Seems like too much, so I converted it into radians, and got 4.63 which is in my opinion a more feasible answer, but I thought I was in radians already...
Homework Statement
A 10m centrifuge can spin at a linear velocity of 17.3 m/s and brake to a stop in 80 seconds
a)What is the torque produced?
b)What is the centripetal acceleration?
c)What is the centripetal force an an 80kg astronaut?
Homework Equations
torque, see below
[tex]a_{c}=\frac{v_{T}^{2}}{r}[/tex]
[tex]F_{c}=\frac{mv_{T}^{2}}{r}[/tex]
The Attempt at a Solution
This is another one that I have not tried. I still feel like I'm not given enough information. How can I find the torque without a force (a mass to find the force). I can't use the 80kg astronaut, as far as I know, otherwise it would have been the first question asked.
For the others, it looks like I could just plug and chug into the equations.
Please and thank you!