## Friction – Numerical

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Standing on an icy surface ,a man of mass 60 kg  throws a stone of mass 3 kg horizontally at a velocity of 8 m/s  . How far does he slide back? Coeff of friction -0.02

## Force and Motion – Numericals

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1.      Find the magnitude and the direction of the net force on an object given that the following forces act on the object at the same time:  20N east, 10N down, 30N west, 50N down, and 30N up. (5 marks)

2.      Human nerve impulses travel at about 10 m/s. Estimate the minimum reaction time from the moment you perceive an obstacle in front of your car and the moment that your foot receives the command to press on the brakes. Consider your height as 1.79m.  If the car is traveling at 50 km/h, how many meters will you travel in this time? (4 marks)

3.      A 500  kg rocket accelerates straight upward from the ground at 70 m/s2. What is the force (thrust) provided by the engine?  (3 marks)

4.      A rope can withstand a maximum tension force of 400N before breaking. If we use the rope to pull a 15 kg bucket of water from a well, what is the maximum acceleration upward we can use without breaking the rope?  (4 marks)

5.      What is the centripetal force acting on an object with a mass of 25 kg moving at a velocity of 15 m/s in a circle with a diameter of 7 m?  When the object is moving with circular motion, are the forces balanced on the object? Why or why not?  (4 marks)

Posted By Emma Richard

## Angular Frequency (Omega) displacement

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I meditate regularly. Stay with me, it gets interesting.
Recently I had an experience I need help understanding.
Briefly.
I created, in my imagination, a tree representing my spiritual body.
My roots(below my feet) descend into the Earth.
My trunk is my physical body.
My branches extend into the cosmos.
That’s the image I started with and have been practicing/refining for about a year now.
Recently:
I started “*hearing,” if you can call it that, instructions on how to use the tree metaphor I created.
I heard, “Use your branches to tune-in (like a radio antenna) Gamma frequency waves.”
I heard, “Use your roots to tune-in Theta frequency waves.”
I heard, “Send both to the center of your heart”
(removing some energetic mechanics for brevity)
I heard, “Point them at each other using ^^ energy mechanics, in the center of your heart.”

This may sound out of the Physics arena and firmly in the Meta-Physical arena, I understand, please continue.

My question is thus;
Can Gamma waves interact with Theta waves creating an offset or diffusion of frequency wave patterns resulting in a 3rd Frequency wave pattern?

I was shown/told/insta-learned that this creates an Omega wave displacement field where more metaphysical stuff can then occur within.

*I don’t really “hear” anything. I use that term because it is easier to convey meaning. It is actually more like a hologram of dense information packets that I have called insta-learn. I instantly know things and can manipulate the “image” to “see” the information transference in more detail, just like a 2D hologram plays out its parallax as you move it side to side.

Briefly:
My limited experience using this method is that after I create the displacement field I can breathe into this new non-local space, I can feel it as well. It feels a lot like when you quickly drop on a roller coaster, weightless, for the lack of a better word.

Thank you so much for reading.
If this is not your bag please consider passing it along to someone who fancies themselves a Neuro-naut AND Physicist.

All The Best,

Posted by Gerald

## Numerical problem based on Gravitation

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Two metallic spheres of mass M are suspended by two strings each of length L.The distance between the upper ends of the strings is L.The angle which the strings  will make with the vertical due to mutual attraction of sphere is (if each mass horizontally moved by a distance of L/4 due to mutual attraction)

The following diagram explains the situation.

From the diagram,

$tan\theta&space;=\frac{4Gm}{l^{2}g}$

or

$\theta=tan^{-1}\left&space;(&space;\frac{4Gm}{l^{2}g}&space;\right&space;)$

Refer to The Pearson Guide to Objective Physics for Medical Entrance Examinations for more of such problems

## Some questions for practice – Atoms and Nuclei

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These are the frequently asked questions/portions and one should definitely practice these.

1. Rutherford’s alpha scattering experiment (Experimental arrangement, observations, conclusions and the Rutherford atom model with appropriate diagrams)
2. Derive expression for the distance of closest approach in Alpha Scattering Experiment.
3. Define impact parameter
4. tate Bohr’s postulates.
5. Derive Rydberg formula
6. Show that the nuclear density is a constant for all nuclei.
7. Explain Hydrogen spectra.using Rydberg formula and energy level diagrams

## Relationship between intensity of radiation and distance

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what is the relationship between the intensity of the Y (gamma) radiation coming from a mono energetic point source and the distance to the source??

## Work Done in pulling up the hanging part of a chain on to a table

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A uniform chain of length L and mass M is lying on a smooth table and one-third of its length is
hanging vertically down over the edge of the table. If g is acceleration due to gravity, calculate the
work required to pull the hanging part on to the table? Is it zero?

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