Relative Definition and 1000 Threads

What speed does a ship traveling through deep space need to travel at for 1 day on the ship to equal 1 day on earth?

Homework Statement 2 cars with velocities 10 m/s and 20 m/s are traveling in opposite directions, having uniform retardation of 2m/s^2 and 1m/s^2 respectively. Find minimum separation between them such that they don't collide. Homework Equations $$v^2=u^2 + 2as$$ $$V_{12}=v_{1}-v_{2}$$ The...

Can you explain why cosine theta is vertical, and sin theta is horizontal on this example? I am confused.

Per my layman's understanding, the apparent force of gravity, as explained by the general theory of relativity, is actually the result of rectilinear motion at uniform speed through warped spacetime. 1. If that's the case, what actually causes gravity for objects at rest with respect to the...

Homework Statement Relative motion problem: A child in danger of drowning in a river is being carried downstream by a current that has a speed of 2.4 km/h. The child is .3 km from the shore and .4 km upstream of a boat landing where a rescue boat sets out. a) If the boat proceeds at a maximum...

Homework Statement In an action-adventure film, the hero is supposed to throw a grenade from his car, which is going 79.0 km/h , to his enemy's car, which is going 125 km/h . The enemy's car is 15.9 m in front of the hero's when he let's go of the grenade. If the hero throws the grenade so...

I have a couple of wonderings about relative humidity under different circumstances, During hot weather periods RH gets high. Is this because water evaporates from oceans and such? Shouldn't how weather result in low RH since hot air can hold more moisture? During the winter RH usually gets...

Homework Statement The compass in a plane indicates that the plane is pointed due east; its air speed indicator reads 212 km/hr. There is a steady wind blowing from the north with a speed of 60.0 km/hr. What is the speed of the plane with respect to the ground? Homework Equations...

Homework Statement For a generic function y=f(x) which is twice-differentiaable, is it possible for there to be a curvature on the curve of that function that is greater than the curvature at its relative extremum?Homework Equations The Attempt at a Solution From visualization and a sketch...

Homework Statement A Red Cross airplane is traveling horizontally east at velocity v_0 = 80.0 m/s and height h = 350 m above the ground. The plane carries emergency supplies for a village inaccessible by road. The plane will drop the package (without a parachute) into a pile of soft hay...

Hi guys, I consider the qm-derivation of the electronic states of hydrogen. There are two different derivations (I consider only the coulomb-force): 1) the proton is very heavy, so one can neglect the movement 2) the proton moves a little bit, so one uses the relative mass ##\mu## The...

Homework Statement A person looking out the window of a stationary train notices that rain drops are falling vertically down at a speed of 5.0 m/s relative to the ground. When the train moves at a constant velocity, the raindrops make an angle of 25° when they move past the window. How fast is...

Homework Statement You are traveling on a bike, moving at a constant speed of 20,0 km/h. You just finished eating an apple, and you wish to pop the core into a trash bin located by a busstop.The bin is 3,00 m from the edge of the road (where you are biking). You throw it at a point 4,00 m...

Homework Statement You wish to paddle a boat across an 82 m wide river and land at a boathouse that is 14 m downstream of your starting point. If the current in the river is uniform at 0.50 m/s, how fast and in what direction do you need to row to reach the boathouse in 2.0 minutes? Homework...

Homework Statement You are traveling on an airplane. The velocity of the plane with respect to the air is 110 m/s due east. The velocity of the air with respect to the ground is 39 m/s at an angle of 30° west of due north. What is the heading of the plane with respect to the ground? (Let 0°...

Homework Statement [/B] Relative frequencies of amount purchased and method of payment Cash Credit Debit $<20 .09 .03 .04 $20-$100 .05 .21 .18 >$100 .03 .23 .14(a) What...

Homework Statement A "moving sidewalk" at an airport moves at 1.5m/s and is 12 m long. A person enters the sidewalk and walks at 1.8 m/s relative to the sidewalk. A)How much time is required for the person to reach the opposite end if the person walks in the same direction as the sidewalk is...

Homework Statement In hot pursuit, Agent Logan of the FBI must get directly across a 1200-m-wide river in minimum time. The river's current is 0.80 m/s, he can row a boat at 1.60 m/s, and he can run 3.00 m/s. Describe the path he should take(rowing plus running along the shore) for the minimum...

Homework Statement A motorboat can move with a velocity of 10.0 m/s, with respect to the water in a river. The river is flowing at 4.00 m/s due east. (a) Calculate the direction (Give the angle with respect to one of the compass directions.) the motorboat must be pointed so that it moves due...

Homework Statement Danielle bikes at a steady rate of 4.0 m/s south along the bank of a river. Summer is rowing her kayak heading south down the river; she can row at a constant rate of 2.0 m/s in still water. There is a 5.0 meter wide bridge that spans the river and the bike trail. a) If it...

Homework Statement Spherical capacitor with two linear and uniform dielectrics with relative permitivitty Ɛr1 and Ɛr2 is connected to constant voltage U. When second dielectric is removed, intensity of electric field by inner electrode is reduced by 1/3, and electric field by outer electrode...

Hello PF. Re.Einstein's thought experiment in which he asks, what is the speed of light as seen from a moving train. He concludes it can't be c-v as the speed of light is always c. Hence time and length must vary. My question is, If the light's speed is relative to the train, why isn't the...

Homework Statement Homework EquationsThe Attempt at a Solution This is actually part of the solution that was provided by the professor. However, I do not fathom two portions of the steps taken (written in orange). Part of the solution is in the picture below. Please help

I know a similar question has been asked but I'm still kind of stumped. Imagine the Earth on the left and a small mass to it's right separated by some distance h. You are in the frame of reference where the Earth and the small mass are moving to your right at some speed v. So, both the Earth...

<<Moderator note: LaTeX corrected>> Problem: > Two cars A and B move with velocity ##60 kmh^{-1}## and ##70 kmh^{-1}##. After a certain time, the two cars are 2.5 km apart. At that time, car B starts decelerating at the rate 20 kmh-2. How long does Car A take to catch up with Car B? I tried to...

Homework Statement James is running west wrt the ground and Billy is running east wrt the ground, but twice as fast as James. How does the relative velocity of James wrt Billy differ if they are running toward each other or away from each other? Explain. *wrt = with relation to* Homework...

I meant to say fast moving "objects" in the title, my bad... my title kind of sucks https://en.wikipedia.org/wiki/Relativistic_electromagnetism#The_field_of_a_moving_point_charge That section is basically what my questions are about. I want to know generally about the overall forces. Two...

Homework Statement So I am in an elevator throwing a ball in an air, straight up and down, about 1 meter from my hand. The elevator is moving upwards at a rate of 2 m/s. From an observer on the ground, would they see the ball reach its peak at the same instant that I do? If not what is this...

Homework Statement Sue rows her boat at 4.5ms. The velocity of the river flow is 2.5ms. What is sues velocity against the flow relative to the water. I can't wrap my head around the question, since sues actual velocity against the flow is 2ms. This should mean she is moving backwards 0.5ms...

If two particles have velocities v1 and v2 in a rest frame, how do we prove that the relative lorentz factor is given by : γ(r)=γ(1)γ(2)(1−v1.v2) and why is this quantity lorentz invariant

I spend a lot of time here helping newbies understand that it simply is not meaningful to talk about motion without any reference what it is that the motion is relative to. Today, I had THE most visceral reminder of that that I think I've ever had. My car's idle has somehow gone to being set...

Homework Statement From a lift moving upward with a uniform acceleration 'a', a man throws a ball vertically upward with a velocity v relative to the lift.The ball comes back to the man after a time 't' Show that a+g = 2v/t Homework Equations s=ut+1/2gt2 The Attempt at a Solution I know this...

There is no such thing as absolute motion or rest. This is because one can record the speed of an object moving relative to it and find that it is in motion. The same holds for the object in motion. An observer on the object will observe the other observer moving relative to him. The measured...

Can relative maximum and minimum points exist when a function is defined at say x=c, however the derivative does not exist or tends to infinity? Ie the graph of. F (x)= |x|, for x=c=o. If I am correct the relative minimum is at o, can it also be the abs minimum? I recalled the theorem by...

A wavefunction of a single particle (ignoring spin etc) is a three dimensional object mapping to 3-D physical space. The wavefunction of two unentangled particles is separable as a product of two independent 3-D wavefunctions. If the particles are entangled, the states cannot be separated, the...

Homework Statement A force P is applied to the rod which rests on a horizontal table. The following accelerations are produced. aA= 3.6m/s2 to the right, α of the rod = 6 rad/s2 CCW. Determine the acceleration of point G and B Homework Equations aG=aA+aG/A aG=aA+[(aG/A)tangential +...

Greetings, Do we use Absloute refractive index when finding crtical angle ? if it was two mediums ( not vacuum or air) how would i calculate the critical angle ? I mean i get confused when I find relative refractive index because sometimes i get sine inverse greater than 1 which give no...

Hi all, Say two events happen in the same place according to one observer (1). They are separated in time by 3 years. According to another observer (2) that is moving relative to the first, the events are separated by 5 years. We can calculate, using the invariance of the spacetime interval...

Homework Statement A rocket moving in space, far from all other objects, has a speed of 3.0 × 103 ms−1 relative to the Earth. Its engines are turned on, and fuel is ejected in a direction opposite to the rocket’s motion at a speed of 5.0 × 103 ms−1 relative to the rocket. What is the speed of...

Homework Statement I've been given a question where I have to find the electric field strength at a point between two charges. Now I understand the mathematics but the question I'm trying to solve says two point charges of value 2C and 3C are position within a medium of relative permittivity...

Here's a physics question that's been giving me trouble. At a height H ,a ball A is thrown upward with a velocity of 20m/s and another B one is thrown down with a velocity of 20m/s and a third ball C is just dropped. Note that it's the same height for all three.I need to find the relation...

Hi all, I feel like I have a misconception about that topic, so I hope I will get an answer for the question: Momentum should be conserved from the same perspective, but does it have to from different perspectives or frames ? I mean we don't agree about sth's velocity, so we don't agree about...

Hello, I am looking at relating two situations under which cyclic energy is applied to a material. Condition 1: A material has been subjected to a force of 1G at 0.1Hz for 47 days. Condition 2: The same material has been subjected to a force of 4.5G at 60Hz for 3600Seconds. Is it possible to...

I have a fan in crawlspace that I can turn on to draw in fresh air. This could reduce the relative humidity by raising the air temperature, and lowering the moisture density. However, air temperature doesn't go up very much because the dirt and foundation wall tend to keep the air at around 55...

Homework Statement A boat is traveling due north at 5 m/s and a passenger on boat A sees another boat, boat b, approaching from south-west (45 degrees) at a speed of 6 m/s. What is boat B's actual velocity? Homework Equations Vrel = Vb - Va The Attempt at a Solution...

Homework Statement I am suppose to calculate the relative entropy between two sets of data: Base set Set 1: A C G T 0 0 0 10 0 0 0 10 0 0 10 0 0 10 0 0 10 0 0 0 * * * * //Randomized 0 0 0 10 0 10 0...

I am confused about Relative Motion.Lets suppose we have one train and two observer.One of them inside the train and the other one is outside.Lets think the outside observer see the train moves a constant velocity v.The observer in the train will be think it is not moving cause of Galileo...

Do two inertial observers in relative motion agree on their relative velocity? Velocity is distance per unit time and they don’t agree on the distance or the elapsed time. If the apparent distance in the prime system is shorter and the elapsed time is longer, then it seems that the apparent...

How the relative angular momentum of two particles can be detect by detector in two particle decay (center of mass frame)? I am curious about the signatures/differentiation between different relative momenta, means how one can decide that it is L=0, L=1,2,3,...? Of course the distribution would...

Homework Statement Two rockets are orbiting a Schwarzschild black hole of mass M, in a circular path at some location R in the equatorial plane θ=π/2. The first (rocket A) is orbiting with an angular velocity Ω=dΦ/dt and the second (rocket B) with -Ω (they orbit in opposite directions). Find...