# What is Phsyics: Definition and 24 Discussions

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1. ### How to determine the same moment of inertia in two different ways?

My solution is now I am asked for the same result but in this form but I don't know where to start.
2. C

### Bullet and chair impulse problem

There is a weapon in which the barrel length is 62 cm and has a muzzle velocity of 450 m / s. A 30 kg wooden chair rests on a wooden floor, the mass of the bullet is 10 g. A bullet penetrates the chair and the bullet lodges in the chair 4 centimeters. How far back, in centimeters, did the chair...
3. ### Electric field produced by a uniform charge density on a wall

I couldn't solve the question. Can you help me?
4. ### I What can we learn from higher derivatives in calculus?

As I have said before, I am in calculus class for the first time. I am doing really well in the class, however because of how my mind works, I’m always asking questions to know more, even when it’s too advanced for me. I just like to ponder and think about “what if” I know it’s probably not good...
5. ### Programs Materials Science (B.Sc.) vs Materials Engineering (B.Eng)

Hello, Looking for some guidance for my son. He will be a senior in high school in the fall and will be applying to university programs in Ontario, Canada. He is leaning towards studying chemistry and/or physics. We (his parents) absolutely want him to follow his passions, but of course are...
6. ### How does thermionic emission work?

I’ve been curious about understanding the mechanism behind themionic emission from what I have read I found that themionic emission happen when the energy from added temperature excess the work function of the material. I also readed when temperature excesses 1000k themionic emission happens but...
7. ### B Does Human Population Growth Impact Lunar Orbit?

The next questions will be in english and spanish, since my birth language is spanish I may be mistaken in a few english words. --------------------------------------------------------------------------------------------------------------------------------------------- Spanish Debo advertir que...
8. C

### Other Physics EE (Extended Essay) Advice: Conservation of momentum

I am not sure if I am at the right place and I hope that I am... For my EE I want to do an investigation on something related to pool table and games so it will definitely be related to momentum. And one of the common techniques in pool games is that the player aims the ball on the rail of the...
9. J

### Determine the angular acceleration and angular velocity

Homework Statement A thin uniform rod (of mass 10.0 Kg and length of 1.20 m) is attached to a friction-free pivot. Initially, the rod is balanced vertically above the pivot (position A in the figure attached). If the rod falls from rest, calculate a. the angular acceleration at position B...
10. J

### Find speed and direction of a particle after collision

SOLVED THANK YOU
11. R

### Is Physics Forums the Ultimate Destination for Chemistry Enthusiasts?

I really like Chemistry. I like physics but not as much as physics. Is it likely that Physics Forums will intrigue me? I found this website trying to find the model on how to solve a chemistry problem but I really enjoy the overall quality of website and was thinking I would give it a shot.
12. ### Kinetic friction in an N,T- system only works in tangential?

Homework Statement Homework Equations F=m*a ΣF(n-direction)= m*a(n)= m*(v^2/ρ) ∑F(t-direction)= m*a(t)\ Ffriction= Fn*coefficient(of friction) The Attempt at a Solution So I tried solving this question and apperently it is way easier than I thought. So I thought the kinetic friction has a...
13. ### Programs Hesitation -- Computer Science, Microengineering or Physics

Hi, I'm applying at a swiss univerity (EPFL) and I already have to pick my major. Here's the thing : I currently love programming. I enjoy finding beautiful ways to solve math programming challenges on the net. (I code in Python). I love automating stuff with programming. I love projects : I...
14. ### Identifying sign conventions for torque and tension

My question arises from trying to get the correct sign convention for a pulley that has two boxes attached by a massless rope. one box is to the left of the pulley and the other box is hanging down below the pulley. If I take the counter clockwise direction to be negative, and set up my...
15. ### Nomenclature phsyics questions

How is this nomenclature read and what is the meaning of the alpha and the n? quote below In terms of the absolute 182Hf abundance, howevever, only AGB (asymptotic giant branch) models of mass ~2 to 4 solar masses are major producers of s process 182Hf in the Galaxy, owing to the combined...
16. ### Is High School Teacher a viable career for a Phsyics PhD or MS?

I was wondering about the situation with regards to teaching high school physics and the extent that it is a viable path for those with a MS and/or a PhD in physics. I have heard it said numerous times, on physics forums and in my physics department, that many high schools are starved for...
17. ### Can someone answer this easy phsyics problem about vertical height

Homework Statement A basketball player achieves a hang time of 0.978 s in dunking the ball. What vertical height will he attain? The acceleration of gravity is 9.8 m/s^2 Answer in units of mHomework Equations ? The Attempt at a Solution 9.8/0.978^2= 10.245 Homework Statement Homework Equations...
18. ### Calculating U-233 Radiation Exposure: 20mSv/yr Equivalent Dose

how many grams of U-233 (halflife of U-233 is 0.1592) would need to have absorbed permanently into your body for the ongoing radiation equivalent does to be equal to 20mSv per year. it decays into alpha-particle at 4.91 MeV
19. ### Engineering, phsyics, and med school questions

Short version: skip straight to bolded questions. I'm a senior in high school trying to figure out what I want to study and what I want my career to be. My main interest is physics, however job prospects seem poor for a physics major. I'd like a decent salary...one that can comfortably...
20. ### Phsyics Kinematics: cannonball shot straight up

http://www.screencast.com/users/trinhn812/folders/Jing/media/5c3b51ea-aed8-4321-964c-126b49a3c1dc F/m = 0.3m/s^2 distance in x direction= 1/2(a)(T^2) By placing v(y) =0 and v(initial)=100 I found the time to be 20 sec. But my answer is 60m. So 1020-60=960m Wouldn't the ball misss the...
21. ### Phsyics problem. I must find distance in Kilometers.

Homework Statement You are driving into St.Louis Missouri, and in the distance you see the famous Gateway-to-the-west arch. This monument rises to a height of 192 m. You estimate your line of sight with the top of the arch to be 2.0 degrees above the horizontal. Approximately how far (In...
22. ### What Causes Divergences in QFT?

more than a proper topic this is a question...my question is if all the divergences that appear in QFT are due to integrals in the form: \int_{0}^{\infty}dkk^{m} with m=-1 (logarithmic),0,1,2,3,4,5,... if not i think that for any other divergences you could express them as...
23. ### Solving Physics Homework Challenges

1. A ball is dropped from a height of 20m and rebounds with a velocity which is 3/4 of the velocity with which it hit the ground. What is the time interval between the first and second bounces? I don't have any idea about dealing with this problem. 2.Explain why a projectile fired from a...
24. ### Physics Contradictions: Examples & Explanations

Hi...I don't know a whole lot about physics but I'm getting there. I have heard a lot of times about different things that have contradicted a few laws of physics. I don't think I've ever seen a specific example, just claims. The last one I heard was on a subatomic level. My question...