# What is Physics 1: Definition and 115 Discussions

Physics (from Ancient Greek: φυσική (ἐπιστήμη), romanized: physikḗ (epistḗmē), lit. 'knowledge of nature', from φύσις phýsis 'nature') is the natural science that studies matter, its motion and behavior through space and time, and the related entities of energy and force. Physics is one of the most fundamental scientific disciplines, and its main goal is to understand how the universe behaves.Physics is one of the oldest academic disciplines and, through its inclusion of astronomy, perhaps the oldest. Over much of the past two millennia, physics, chemistry, biology, and certain branches of mathematics were a part of natural philosophy, but during the Scientific Revolution in the 17th century these natural sciences emerged as unique research endeavors in their own right. Physics intersects with many interdisciplinary areas of research, such as biophysics and quantum chemistry, and the boundaries of physics are not rigidly defined. New ideas in physics often explain the fundamental mechanisms studied by other sciences and suggest new avenues of research in academic disciplines such as mathematics and philosophy.
Advances in physics often enable advances in new technologies. For example, advances in the understanding of electromagnetism, solid-state physics, and nuclear physics led directly to the development of new products that have dramatically transformed modern-day society, such as television, computers, domestic appliances, and nuclear weapons; advances in thermodynamics led to the development of industrialization; and advances in mechanics inspired the development of calculus.

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1. ### Need help on a energy question: Hockey puck sliding across the ice

I first attempted to do Ein = Eloss + Eout because the equation had friction in it but in the answer key they set it as the energy was conserved by doing Ein = Eout, why is it conserved when the puck comes to a stop which means energy was lost? I thought the equation should have been Uspring =...
2. ### Why Does a Free-Falling Object Not Have Zero Final Velocity Upon Impact?

I am super stumped at this question, the answer key is telling me 6.78 downwards, i think I'm reading and observing the question wrong. Isn't final velocity 0 so why can't i do 0 = v0 -9.8(0.25) -2.45 = v0 But when I use the second the equation -2 (displacement of door) = v0(0.25) + 1/2...
3. ### Rating speeds from least to greatest from a position time graph

My answer is R > P > Q = S Since R is more steeper than P the speed is greater, speed is a non-negative unit so i assume that speed of R will be greater than P Speed of P has a positive slope, also the magnitude is positive. Q and S are the same due to the fast that they both horizontal slopes...
4. ### How to Solve Dynamics Exercise Involving Force Representation?

This is the exercise: Please help me ( question 4 and 5). Here is my effort: First, I represented the forces on both objects. Then, i found F⁰ = 5N (question 1) After that, (question 2) + (question 3) I hope it's even correct.
5. ### Kinematic car overtake problem: Don’t know what to do...

This is what I've done so far: 54 km/h = m/s 72 km/h = m/s a = 2,0 m/s^2 A = d_1 = v * t = 15 * 10 = 150 m B = d_2 = v * t = 20 * 10 = 200 m d_3 = d_1 - d_2 = 200 - 150 = 50 m Don‘t know how to continue to solve the problem.
6. ### What's the Future of Physics?

Just a thread to discuss ideas and questions of physics. I plan on becoming a theoretical physicist after I graduate, and feel that enriching discussions here will help further that cause.
7. ### Intro Physics Recommendations on Introductory physics and AP physics 1 books?

Greetings to all. I'm looking for the best textbook for introductory physics that has clear explanations and is problem-oriented. I'd also appreciate any recommendations for textbooks for the AP Physics 1 exam.
8. ### Physics project confusion (effects of length on a pendulum)

We are seeking to design a project where we use a simple pendulum and a motion sensor (that will give us velocity) in order to study centripetal acceleration by essentially changing the length of the pendulum for each trial. This felt simple enough, however our professor insists that we would...
9. ### A greater force? (A train engine pulling two identical cars)

My choice is C, which is "equal to." Here is my reasoning: The engine pulls on car 1, so car 1 is having a force acting on it, which pulls car 1 forward. Likewise, the same amount of force is applied on car 2 by car 1 by moving forward with the same amount of force from the beginning. So it is...
10. ### Solving a Sound Wave Equation in Physics 1: Halliday, Resnick, and Krane

Homework Statement:: This is from 5 ed, Physics 1Halliday, Resnick, and Krane. page 428 about sound waves I have highlighted the equation that I don't understand. How did the author get it? I understand how they get from the middle side to the RHS of the equation, but I don't understand how...
11. ### Courses What do I do to catch up on Physics 1?

I am a nanobiology student about to start her 2nd year. This year I only had 2 physics courses and I did pretty bad in both. As I start my second year I would like to be very prepared in physics since we will have way more of this subject. Are there some books or tips you have to catch up on...
12. ### Conservation of momentum in an oblique launch and projectile explosion

This problem I already solved using another resource (just get the coordinate of the center of mass reach and from it, get to the larger mass. R = (3v02) / (4g)). But I'm having some trouble calculating using moment conservation. Here what I've done so far: $$3\vec v_0 = \vec v_1 +2\vec v_2$$...
13. ### Nolting Theoretical Physics 1, Jacobian Notation Question

On Page 406 of Nolting Theoretical Physics 1 he has the following notation for the Jacobian determinant \frac{\partial( x_{1}, x_{2})}{\partial (y_{1}, y_{2})} = \begin{vmatrix} \left (\frac{\partial x_{1}}{\partial y_{1}} \right )_{y_{2}}& \left ( \frac{\partial x_{1}}{\partial y_{2}}...
14. ### Intro Physics Introduction to Physics: Books for Non-Calculus Learners

Can you recommend books for introduction physics without calculus.That is basic.
15. ### AP Physics 1 Help? Centripetal motion/Kinematics/Friction problem

I think I have solved the first three, and only really need help on question four. For number one, I used Fc = (Mv^2)/R and just rearranged it for velocity so I ended up with v = sqrt(ac * R) For number 2 I used Ff = Fn*mu and got Mg*mu = Ff For number 3 I used w = Ff*d and got w = -Mg*mu*l...
16. ### Rotational Motion and moments of inertia

I have the moment of inertia for the core(initial) and full body(final) but my answer for the moment of inertia for the arms(initial) was incorrect. Arms(initial) moment of inertia:(1/12)(6)(1.7^2)=1.445 this is incorrect for some reason Core(initial) moment of inertia: .9558 Full...
17. ### A golf ball being hit on the moon vs Earth

I am just not sure if I did this properly. My professor hasn't really gone over when to use the range equation but I would assume range would equal the distance traveled therefore can be used for this problem. If not the how would I go about solving this? I did 1/6*9.8=1.63 for g on the moon...
18. ### Courses AP Bio then AP Physics 1 or other way around?

Hey! I’m a sophomore that is scheduling for next year. Hopefully, I will be taking AP Calc BC next year (junior year). As for my science course, I want to take AP Bio and AP Physics 1 before graduating, but we can only take one per year. So would you recommend Physics during my senior year when...
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### Struggling with Physics 1A in Industrial Engineering?

Hello everyone I'm new here, from South Africa. I am currently studying Beng technology industrial engineering. I am doing physics 1a which kinda giving me a problem.
20. ### Finding friction and tension for a train

Homework Statement A UTA Trax train engine can apply 96050 Newtons and locomotive has a mass of 1750 kg. The passenger car has a mass of 949 kg. (A) If the train accelerates at a rate of 1.29 m/s/s, how much friction is present in the passenger car? (Assume the locomotive moves...
21. ### Can we find work done on this particle, and if not, what are we missing?

Homework Statement A force varies with time according to the expression F=aΔt, where a = 2.0 N/s. From this information, can you determine the work done on a particle that experienced this force over a displacement of 0.50 m? Homework Equations W = F*d Vf = Vo + aΔt F = ma The Attempt at a...
22. ### Half Atwood machine: acceleration after inital force

Homework Statement Assume that the block on the table (Figure 1) has twice the inertia of the hanging block. (a)You give the block on the table a push to the right so that it starts to move. If the magnitude of the frictional force exerted by the table on the block is half the magnitude of...
23. ### Calculating the work done from an equation for variable force

Homework Statement The force on a particle is directed along an x axis and given by F = F0(x/x0 - 1) where x is in meters and F is in Newtons. If F0 = 1.5 N and x0 = 4.9 m, find the work done by the force in moving the particle from x = 0 to x = 2x0 m. Homework Equations F = force, w = work, x...
24. ### Other Any physicists that struggled with intro physics?

I’m 3 weeks into my first physics class at college; honors physics 1. I really want to major in physics because it’s really interesting, but I’m finding the class very difficult. Trying to solve the textbook problems and follow the professor’s train of thought is very tough, which is frankly...
25. ### How Is Work Calculated for a Gas and Balloon in Isothermal Expansion?

Homework Statement The question is: One kilogram of a gas with a molecular weight of 35 is contained in a balloon. The initial conditions are 27 C and 0.025 m^3. The gas is slowly heated isothermally until the final volume is 0.05m^3. The atmospheric conditions are 100 kPa and 27 C. The p-v-T...
26. ### Torque and Angular Momentum Vector Question.

Hello. I'm currently entering into a Physics II class at the start of my third semester at UCONN (my first semester was introductory modern physics - kinetic theory, hard-sphere atoms, electricity and magnetism, scattering, special relativity, Bohr model, etc), and finished Physics I off with...
27. ### Courses Worried about receiving a B in Physics 1

Hello everyone, I have just completed my second semester in college, and I ended up receiving a B in my introductory Physics 1 course (Newtonian mechanics and waves). I love physics with a passion, and this course was the reason I switched my major to astrophysics. To be more accurate, my final...
28. ### Vector Notation in Nolting Theoretical Physics 1

On pg. 60 of Nolting Theoretical Physics 1 for the definition of a vector multiplied by a scalar the book shows two little up arrows if the scalar is greater than zero and an little up arrow and then a little down arrow if the scalar is less than zero. Then again on pg. 61 for definition 1.139...
29. ### I How to Calculate Work for a Time Varying Force?

I'm probably misunderstanding something or have confused my self, but while I was studying for calculus (work integration) I realized that we're always dealing with forces that vary with distance like gravity or a spring force, but what if you have an arbitrary force that varies with time? Like...
30. ### How Do You Calculate the Moment of Inertia for a Disk with a Central Hole?

Homework Statement A disk of radius R has an initial mass M. Then a hole of radius (1/4) is drilled, with its edge at the disk center. Find the new rotational inertia about the central axis. Hint: Find the rotational inertia of the missing piece, and subtract it from that of the whole disk...
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### Dynamics and Circular Motion Problem

Homework Statement A 2 kg tetherball swings around a vertical pole attached to two ropes each at a 30 degree angle from vertical. Each supporting rope is 1.5 meters long, and the ball travels at 8 m/s long. Homework Equations The question doesn't ask what they're looking for, so I assume they...
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### AP PHYSICS 1 Kinematics falling with deceleration

Homework Statement Captain American bails out of an airplane and falls 50 meters without friction. When the parachute opens, he decelerate at 2.0m/s2. He reaches the ground with a speed of 3.0 meters/sec. a.) How long is captain america in the air? do= d= vo= v=3m/s t= ? a= -9.8m/s2 ?? (this...
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### AP Physics 1 kinematics problem

Homework Statement The engineer of a passenger train rounding a curve at 30m/s sights a slow-moving freight train 200m ahead on the same track traveling in the same direction with a constant velocity of 10m/s. The engineer of the passenger train immediately applies the brakes, causing a...
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### AP Physics 1 Kinematics problem

Homework Statement Luke Skywalker is making a diving run at the Death Star, approaching in his X-Wing at a rate of 500m/s. (The Death star is hollow, so it has almost no gravity.) Suddenly, at 800 meters from the Death Star, Luke fires his retro rockets. This creates a reverse acceleration of...
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### Rotation problem - AP Physics 1

Hey guys, I'm having trouble understanding this problem that was on an AP Physics 1 sample questions page: So a couple of questions here: (By the way, I know the answer is C) 1. My teacher explained that the net torque here on the assembly would be zero(will ask him again later). Is this...
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### Courses AP Physics 2 without AP Physics 1?

Hey, all! My situation is as follows: I'm an upcoming senior in high school and in the middle of my junior year I developed an interest in physics. However, at my school, AP Physics 1 is taken junior year and AP Physics 2 is taken senior year. I didn't take AP 1 because I was indifferent to...
37. ### Studying Should I take physics 1 and chemistry 2 simultaneously?

During the summer semester, which is around 6-8 weeks. Chemistry 1 was a breeze for me, I scored an A. I've always liked physics in high school, but I've never done physics in over a year. Physics 1 holds 5 credits, and chemistry 2 holds 4 credits. I'm a biology major if that changes anything.
38. ### Calculus Need help preparing for Courant's Calculus

Hello, Just to give you some background info, I'm a software developer looking to make a career switch to Mechanical Engineering (At least I think so). My interests lie in design, complex systems, maglev, rockets and new forms of space propulsion. Before I really commit myself to University, I...
39. ### Is the AP Physics 1 textbook flawed in its explanation of moment of inertia?

Homework Statement [/B] I'm probably missing something basic here but: The moment of inertia of a body does NOT depend on which of the following? (choose 2 answers) A: The angular acceleration of the body B. The distribution of mass in the body C. The angular velocity of the body D. The axis...
40. ### Distance an object travels after sliding and falling from roof

Homework Statement [/B] My physics teacher - "You may like this question, its very structured" Calculate the distance a slate tile falls from a roof The roof is angled at an angle 30 degrees. mass of slate tile is 0.8kg The length of the roof is L=6m The height of the roof above the ground is...
41. ### Calculating Tension in a Revolving Mass: Homework Solution

Homework Statement The figure shows two wires that are tied to a 970g mass which revolves in a horizontal circle at a constant 7.5 m/s. What is the tension in the upper wire? The wires are both 1m long, and are attached to a pole. The radius is cos(30 degrees). It's an equilateral triangle...
42. ### Problem using centripital accel.... Can you check my work?

Homework Statement A student ties a 500 g rock to a 1.0-m-long string and swings it around her head in a horizontal circle. At what angular velocity in rpm does the string tilt down at a 16 degree angle? Homework Equations F = (m*v^2)/r v = r*w The Attempt at a Solution [/B] First I solved...
43. ### Can I take AP Physics 1 while concurrently taking Algebra 2?

Next year, I want to take AP Physics 1 but I am worried that it would be confusing since I would still be learning about Algebra 2. Is it recommended to do this?
44. ### Air-Track Carts & Spring (Energy)

Homework Statement The air-track carts in the figure(Figure 1) are sliding to the right at 2.0 m/s. The spring between them has a spring constant of 140 N/m and is compressed 4.1 cm. The carts slide past a flame that burns through the string holding them together. What is the final speed of...
45. ### Courses Can I catch up on physics 1 & 2 in 3 months?

So I am currently an ME major at CC. I am probably going to transfer to a university to study physics next fall but there is one problem... I took physics 1 & 2 at a community college that is very heavily focused on their engineering program. Because of this, I only learned things in physics 1...
46. ### Intro Physics projectile problem: Archer fish and grasshopper

HOMEWORK SUBMITTED IN WRONG FORUM, SO NO TEMPLATE I uploaded an image of the problem, it seems to be fairly straight forward. However, my textbook indicates the answer as being 6 m/s, I am consistently getting 3 m/s. Any help would be appreciated! Because there is no air resistance, the...
47. ### Simple harmonic motion calculations from doubling the mass.

Homework Statement What will the new amplitude be if A=.117m and the mass is 0.1kg. The spring constant is 3.587N/m and the mass is then doubled. What is the new velocity max? What is the acceleration max? Homework Equations Fnet= -kx, vmax=A(ω), ω= √k/m The Attempt at a Solution...
48. ### Courses My physics 1 & 2 teacher skipped so much material....

I go to a community college for mechanical engineering and I always thought that physics 1 and 2 were way too easy and that my teacher probably skipped a lot of important material. One of my friends just transferred to a university to major in physics and he's been telling me that we didn't...
49. ### Calculate the distance the sled travels

Homework Statement A sled starts with an initial speed of 5.0 m/2 at the top of a 16 meter high ski jump. The ski jump makes an angle of 53 degrees relative to the horizontal. There is a coefficient of kinetic friction of 0.5 between the sled and the ski jump. Calculate the distance from the...
50. ### Are AP Physics 1 FRQ's appropriate for First Year Student

This post is directed at the college professors and graduate TA's on the forum. You may or maynot be aware that the College Board recently redesigned the algebra/trig based AP physics course and split it into two - 1 year courses. The first year effectively covering mechanics through waves and...