Relative velocity Definition and 407 Threads

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...

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...

Hi Friends , I had a discussion with a funny person last night. He said the following argument : Suppose there are 21 objects including the one object under consideration. Each of the 21 objects move with a velocity. Since there are 21 objects, for the object we are considering has 21...

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...

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...

Homework Statement A certain quasar recedes from the Earth with a speed of .87c. a jet of material is ejjected towards the Earth at .55c relative to the quasar. find speed of ejected material relative to the earth Homework Equations u = u'+v / 1 + u'v/c^2 The Attempt at a Solution guessing...

Homework Statement An ant with a velocity of 20mm/s [W] crawls on a stick that is being dragged [W25 N] at 50mm/s. what is the velocity of the ant relative to the ground? Homework Equations Let A = ant, Let S=stick, Let G=ground, Let N and W be positive. Vag=?, Vas=20mm/s [W], Vsg=50mm/s[W25N]...

I'm using the the Doppler formula to calculate the relative velocity between the approaching and receding filaments of the crab nebula: Δλ/λnaught = v/c Change in wavelength/ wavelength = velocity/ speed of light I have reworked the formula as v= c(Δλ/λnaught) When I plug in the values I get...

Homework Statement Particles ##a## and ##b## move in opposite directions around a circle with angular speed ##ω##. At ##t = 0## they are both at the point ##\vec{r} = l \hat{\jmath}## where ##l## the radius of the circle. Find the velocity of ##a## relative to ##b## Homework Equations...

Since relative velocity time dilation is due to an increase in velocity, with a person moving faster moves through time slower than those on earth, does it follow that it's possible to move slower than the Earth and therefore move through time faster than them? Because the Earth is moving...

2. (a) is the question I'm stuck with Homework Equations I know that 3m/s is the Velocity of the man relative to the water and the Velocity of the man is 8m/s and is represented by the vector pointing in the direction theta downstream but I just can't get my head around this question, probably...

I'm still very early on in my reading, so forgive me if this question isn't coherent. In the "historical introduction" section of the 1920 University of Calcutta translation of the original papers of Einstein and Minkowski available via the MIT online archive, mention is made of the fact that...

I'm having trouble understanding how the lorentz transformations are posed intially. Why can different observers agree on their relative velocity? I don't understand why this velocity is exempt from all of the other relativistic phenomena that occur. Also, in the initial derivation, I'm told...

Homework Statement If you were to throw a large log over the edge of the Grand Canyon and it took 5.65 seconds to hit the ground, calculate the velocity of the log at impact in m/s and calculate the distance the log fell in feet. Homework Equations vf=vi + at, s=d/tThe Attempt at a Solution...

Homework Statement "To illustrate this principle, consider a plane flying amidst a tailwind. A tailwind is merely a wind that approaches the plane from behind, thus increasing its resulting velocity. If the plane is traveling at a velocity of 100 km/hr with respect to the air, and if the wind...

1. Problem Statement: What is the velocity of John relative the bus in each of the following situations: A) John is sitting on the street and the bus is moving at 30m/s toward him B)John is sitting in his car traveling North at 25m/s toward a stationary bus? C)John is sitting in his car...

A police car is chasing a stolen car ahead of it. If the police car is traveling at 150 km/h (N) and the stolen car is traveling at 120 km/h (N), then determine: a) velocity of police car relative to ground b) vel. to the pol. car relative to the stol. car c) vel of stol car relative to the pol...

I'm still pretty much a virgin when it comes to the serious study of physics, so I apologize if this question is a bit ridiculous. Is the lack of specificity of velocity and position according to the uncertainty principle somehow related to the lack of meaning of velocity without an independent...

EURONCAP front crash test involves crashing a car moving at 64 kph onto a deformable barrier at 40% of the total vehicle width. According to the EURONCAP website, this is equivalent to two vehicles crashing into each other at 55 kph. How did they arrive at this figure? I presumed that the...

Umm, so as far as I understand velocity is speed in a direction. So if I'm going North at X Km/h and another guy goes south, he'll go at -X Km/h. So anyways, the formula for relative velocity, for example V(AB) is V(A)-V(B). So let's say two trucks are going at 70 m/s towards each other...

Homework Statement In a particular frame of reference a particle with 4-momentum ##P_p## is observed by an observer moving with 4-momentum ##P_o##. Derive an expression for the speed of the particle relative to the observer in terms of the invariant ##P_p.P_o## I am completely stuck on this...

Homework Statement If two particles have velocities u and v in frame S, find their relative speed in frame S'. Homework EquationsThe Attempt at a Solution Isn't it strange that the relative speed doesn't depend on the velocity of the frame, ##\vec s##? Since the two particles have velocities...

Homework Statement In a given inertial frame two particles are shot out simultaneously from a given point with equal speeds u at an angle of 60 degrees with respect to each other. Using the concept of 4-velocity or otherwise, show that the relative speed of the particles is given by ##u_R =...

in swimmer-river physics problems ,velocity of swimmer in still water=velocity of swimmer with respect to ground OR velocity of swimmer in still water=velocity of swimmer with respect to river which of these is correct .I am really confused.

How come relative velocity of the beams can be expressed by v_{12} = \left| \vec{v}_1 - \vec{v}_2 \right| = \left|\frac{\vec{p}_1}{E_1} - \frac{\vec{p}_2}{E_2}\right| where \vec{p}_{1,2} and E_{1,2} is the momenta and energies of incoming particles, respectively? Similar equation is in Peskin &...

Q. Two particles start simultaneously from the same point and move along two straight lines, one (particle A) with uniform velocity v and other (particle B) with a uniform acceleration a. If ##\alpha## is the angle between the lines of motion of two particles then the least value of relative...

Are the vectors resolved correctly? I get a different answer to this question(well my diagram itself is different). How can ##\beta## be greater than ##\alpha##? Isn't it that here ##\alpha## should be in place of ##\beta## and ##\beta## in place of ##\alpha## and both ##V(rain,woman)## and...

Homework Statement A stone is dropped from a balloon at an altitude of 300 metres. How much time is required for the stone to reach Earth if: (1) Balloon is ascending with a velocity of 5 m/s, (2) Balloon is descending with a velocity of 5 m/s (3) Balloon is stationary Disregard air...

Homework Statement A ship goes from A to B at v_1=10 km/h and from B to A at v_2=16 km/h Find: (1) the average velocity of the ship, and (2) the velocity of the river current. Homework Equations v_{avg}=(v_1+v_2)/2 v_{AC}=v_{AB}+v_{BC} The Attempt at a Solution...

A light plane is headed due south with a speed relative to still air of 185 km/h. After 1 h, the pilot notices that they have covered only 135 km and their direction is not south but 75˚ south of east. What is the wind velocity? I know I have to set up a triangle and solve...

Homework Statement The last stage of a rocket, which is traveling at a speed of 7600m/s, consists of two parts that are clamped together: a rocket case with a mass of 290.0 kg and a payload capsule with a mass of 150.0kg. When the clamp is released, a compressed spring causes the two parts to...

Q: The pilot of an aircraft flies due east relative to the ground in a wind blowing 20 km/h toward the south. If the speed of the aircraft in the absence of wind is 70 km/h, what is the speed of the aircraft relative to the ground? I set up the vector of wind WRT ground pointing due south...

Here's a weird question where I don't quite know if length contraction or time dilation play a role. Say I have 2 spaceships moving towards each other. rest length of spaceship A is La and spaceship B is Lb. The pilot in A determines that time taken for the spaceship B to traverse the length...

Homework Statement The problem is worded thus: You are on an airplane traveling 30° south of due west at 130 m/s with respect to the air. The air is moving with a speed 30 m/s with respect to the ground due north. (a) What is the speed of the plane with respect to the...

A simple experiment can be build to demonstrate a possible contradiction between thinking theory and reality. Use two hand electrical light torches set upon a table and back to back. Switch them on simultaneously, and calculate the relative velocity of their opposite leaving flashes...

Homework Statement A canoeist wants to travel straight across a river that is 0.10km wide. However, there is a strong current moving downstream with a velocity of 3.0km/h. The canoeist can maintain a velocity relative to the water of 4.0km/h. a) In what direction should the canoeist...

Homework Statement Solved Homework Equations The Attempt at a Solution Solved

The swimmer will move in the direction of resultant of his velocity and velocity of water. Draw the diagram and the try to solve it.

Homework Statement I know that if you have 2 observers, "A", one at rest and the other "B" moving wrt "A" and if the moving observer shoots a projectile, then we can calculate the velocity of the projectile wrt "A" using the standard equation shown below. I was thinking what equation would...

A flat rectangular barge,48m long and 20m wide, is headed directly across a stream at 4.5 km/h. The stream flows at 3.8 km/h. What is the Velocity, relative to the riverbed, of a person walking diagonally across the barge at 5km/h while facing the opposite upstream bank? Hi Guys, having some...

Homework Statement A spaceship travels from Earth to the vicinity of the star that is measured by astronomers on Earth to be six light-years away. The spaceship and its occupants have a total rest mass of 32 000 kg. Assume that the spaceship travels at constant velocity. The time taken as...

if we know the relations between time and distance at the moving frame and stationary frame why can't we derive the velocity in the moving frame in a such way. Please point out my mistake. See attachment.

If a spaceship travels a distance of one light year as measured from Earth in one year's time as measured from the spaceship what is the relative velocity for earth-ship. Also how far did the pilot travel according to the pilot and how long was the trip according to an earth-clock? I found...

Homework Statement An airplane pilot sets a compass course due west and maintains an airspeed of 225km/h . After flying for a time of 0.470h , she finds herself over a town a distance 119km west and a distance 14km south of her starting point. 1) Find the magnitude of the wind velocity...

Okay here goes! A boat "A" travels due north at a velocity of 18km/h , and a boat "B" travels south-east at 15km/h. a) Calculate the velocity of "A" relative to "B". b) If "B" is initially 30km north of "A", calculate the shortest distance between the two boats during the motion. Right, so I...

Homework Statement A motorboat is observed to travel 10 km/hr relative to Earth in the direction 37° north of east. If the velocity of the boat due to wind ONLY is 2 km/hr westward and that due to current is 4 km/hr southward, what is the magnitude and velocity of the motorboat due to its own...

I am really confused about relative velocity when one frame is rotating. Is it possible to have velocity/acceleration of A relative to B and velocity/acceleration of B relative to A not having same magnitude and opposite direction? Any explanation will be helpful! Thank you

A boat is traveling upstream at 14 km/h with respect to a river that is flowing at 6 km/h (with respect to the ground). A man runs directly across the boat, from one side to the other, at 6 km/h (with respect to the boat). The speed of the man to the ground is ____? Attempt: vPG = vPB +...

Homework Statement A uranium atom (U), traveling with a velocity of 5.00 x 10^5 m/s relative to the containing tube breaks up into krypton (Kr) and barium (Ba). The krypton atom is ejected directly backwards at a velocity of 2.35 x 10^6 m/s relative to the barium after separation. With what...

Homework Statement The escalator that leads down into a subway station has a length of 30.0 meters and a speed of 1.8 meters/second. relative to the ground. A student is coming out of the station by running in the wrong direction on this escalator. The local record time for this trick is 11...