Relative Definition and 1000 Threads

Homework Statement A boat is crossing the river with a speed of 6.2 m/s east relative to the water. The river is flowing north at a speed of 2 m/s and is 750 m wide. a) What is the speed of the boat relative to the Earth? b) How much time is required to cross the river? c) How far downriver...

Hi everyone Homework Statement Take a look at the drawing. Now I found out the differential equation for this is: \mu \vec{r}''=-k \vec{r} mu is the reduced mass Now I shall show, with using the generel solution for this differential equation (in cartesian coordinates), that the...

Homework Statement Space ships A and B, each having a proper length of 100m, pass each other moving in opposite directions. According to the clocks on ship A, the front end of B takes 1.5 x 10^(-6) s to pass the entire length of A. a) what is the relative velocity of the two ships? b)...

Homework Statement motor is mounted on top of lift. a)if p moves by y, what is the displacement of Pt A? Prove that Vp=-3Va. b)If motor unwidns cable at const rate 2m/s, what is vel of cable wrt lift. Prove vel of lift is 0.5m/s Homework Equations The Attempt at a Solution I...

https://www.physicsforums.com/showthread.php?p=3577768#post3577768" has caused me to question my assumptions. If a target of observation is moving at relativistic velocities but its distance does not change wrt the observer, is it observed to be experiencing time dilation? Alice stands at...

Imagine an Aeroplane held above the Earth's surface for 12 hours, having no contact with the surface of the earth. Suppose that the initial location at time t=0 is Asian continent. So after t = 12 hours, can we expect the aeroplane to be in some other continent or will it be in the same location.

Hi, I am curious whether that when the Earth is in its closest position to the Sun, the Suns gravitational pull has a direct effect on the Earths orbital speed. Since the speed of an object has an effect on time. Would the increase in speed affect time in general. Of course the time is...

Homework Statement While driving north at 25 during a rainstorm you notice that the rain makes an angle of 38 with the vertical. While driving back home moments later at the same speed but in the opposite direction, you see that the rain is falling straight down. a)From these observations...

A river flows east to west at 3.0 m/s and is 80 m wide. A boat, capable of moving at 4.0 m/s, crosses in two different ways. (a) Find the time to cross if the boat is pointed directly north and moves at an angle downstream. (b) Find the time to cross if the boat is pointed at an angle upstream

Homework Statement A shortstop running at 2.0m/s toward third base catches and throws a ball toward home plate at 35m/s. IF the shortstop and catcher are lined up in a direct line of when the shortstop throws the ball, a)at what angle to his body should he throw in order for the ball to...

Homework Statement A man can row a boat at 4 m/s in still water. The current in a river is 2 m/s. The river is 40 m wide. If he wants to cross the river in the smallest possible time at what direction should he aim the boat? Given: V[B,E] = 4m/s V[W,E] = 2 m/s Down is negative. Homework...

Homework Statement The relative population of two atomic population states in equilibrium is given by Boltzmann Distribution: n1/n0 (proportional to) e^(-ε/(κT)) , where ε is the energy difference between the two states, T is the temperature and κ is the Boltzmann constant = (1.38 x...

Homework Statement A canoe has a velocity of 0.470m/s southeast relative to the earth. The canoe is on a river that is flowing at 0.490 m/s east relative to the earth.Find the magnitude of the velocity Vc/r of the canoe relative to the river. there is a graph: Vr/e pointed directly on the...

I understand the concepts behind SR and Lorentz transformations and was explaining the basics to my son by illustrating the classic laser-beam-in-a-train-car explanation. But then I started thinking... If I was in a boxcar w/ a clear wall and was throwing a ball straight up, measuring the time...

Not sure if this belongs in the SR forum, but here goes. I understand the concepts behind SR and Lorentz transformations and was explaining the the basics to my son by illustrating the classic laser-beam-in-a-train-car explanation. But then I started thinking... If I was in a boxcar w/ a...

Homework Statement A missile is launched from a fighter jet cruising horizontally at a speed of 280 m/s, at an altitude of 1800 m. The initial velocity of the missile relative to the fighter jet is 160 m/s, in the forward direction. The missile is powered by its own engine, which provides it...

Relative energy of simple 2 particle system (confused!) Ok so I have a simple question which I feel I should know the answer to: Setup: Two particles of different mass.. say M and m (where M > m) are moving past each other by some constant velocity. If we view the energy of the system from...

Homework Statement Car A is traveling east at 20m/s toward the intersection, car B from rest 40 m North of the intersection and moves south steadily gaining speed at 2.0 m/s^2. six second after A crosses the intersection find 1) position of B relative to A 2) the velocity of B relative to A...

Homework Statement Two airplanes taxi as they approach the terminal. Plane 1 taxies with a speed of 11 m/s due north. Plane 2 taxies with a speed of 8.5 m/s in a direction 20 degrees north of west. a) What is the magnitude of the velocity of plane 1 relative to plane 2? b) What is the...

Dynamics Help Needed! Relative velocities problem Homework Statement see link: http://www.flickr.com/photos/55153239@N03/6199846646/ Homework Equations Can you please help me solve this problem? I have 3 unknowns: Va, Vb, and Thetha; but only two equations Vb(cos(theta)) -...

Homework Statement A Boeing is flying east at 150 km/hr, After 2 hours it is 350 km East and 74 km south of its starting point. What is the magnitude and direction of the wind velocity? Homework Equations Not sure if anyThe Attempt at a Solution Well I really had no idea what to do so i...

Homework Statement A helicopter velocity relative to the ground is flying south for exactly .75hours. A wind blows and the helicopter ends up 30 Km in a southwesterly position away from her starting point. the helicopter speed relative to the ground is 50km/hour. What is the direction and...

if a rocketship in space is approaching the speed of light and its relative mass is increasing then i assume the fuel mass is increasing which would make it more potent the closer the ship gets to the speed of light which would give it infinite force when the ship reaches the speed of light...

Homework Statement http://imgur.com/EcjIaHomework Equations I already got the first part (v_b/a) i need to find r dot and theta dotThe Attempt at a Solution well i got v_b/a. for r I was thinking of using sqrt(y^2 +x^2) at the r and taking derivatives of that. i don't quite understand polar...

Homework Statement 1) A boy is floating on a raft in a river. THe water flows at a speed of 12m/s east. The boy's feet kick the water,causing a velocity of 2m/s at an angle of 43 degrees north of east. Using Vector components, calculate the magnitude of the raft's velocity. 2)One vector...

Homework Statement A plane traveling horizontally to the right at 100 m/s flies past a helicopter that is going straight up at 20 at 20 m/s. From the helicopter's perspective, the plane's direction and speed are: a) Right and up, less than 100 m/s. b) Right and up, 100 m/s. c) Right and...

A swimmer crossing a river proceeds at an absolute speed of 2.5 m/s on a course oriented at a 45degree angle to the 1 m/s current. Given that the absolute velocity of the swimmer is equal to the vector sum of the velocity of the current and the velocity of the swimmer with respect to the current...

Homework Statement (In textbook, given a figure, I cannot redraw that figure in this applet, so I shall describe the question in words) I am given a rectangular xy coordinate system determined by the unit basis vectors i and j and an x'y'-coordinate system determined by unit basis...

A swimmer who achieves a speed of 0.75 m/s in still water swims directly across a river 72 m wide. The swimmer lands on the far shore at a position 54 m downstream from the starting point. (a) Determine the speed of the river current. (b) Determine the swimmer?s velocity relative to the shore...

Homework Statement Person X jumps off a cliff from a height of h to the ground. On the way down X fires off a boaster which has a positive acceleration compared to gravity. Find in terms of t(time in seconds), mass, and gravityHomework Equations x=x0+(vt^2)+1/2(at^2) F=maThe Attempt at a...

Homework Statement (a) When the displacement in SHM is one-half the amplitude A, what fraction of the total energy is kinetic energy? What fraction is potential? The Attempt at a Solution I tried finding a ratio of KE/t, where t=KE+PE and PE/t but I got answers that didn't...

If an object's mass increases as it nears the speed of light, would its gravitational field also change, and therefore change its affect on space time? If this is true, would a smaller object traveling behind it be pulled faster as a result?

Homework Statement A blimp is ascending at the rate of 7.6 m/s at a height of 67 m above the ground when a package is thrown from its cockpit horizontally with a speed of 4.5 m/s. (a) How long does it take for the package to reach the ground?(b) With what velocity (magnitude and direction)...

Homework Statement Explain what you understand by the term Relative Atomic Mass The question is equal to three marks, though i don't think I've put enough for all the marks: The Attempt at a Solution The mass of an atom relative to one atom of carbon-12. I would think that's only...

Homework Statement 46-Ti 47-Ti Using the information in Table 1.1, calulate the relative atomic mass of this sample of titanium, Give your answer to 3 significant figures. Homework Equations The Attempt at a Solution I only know how to figure out the relative atom mass if...

I was sitting in my bed thinking about how time can be relative after i heard about those experiments with atomic clocks slowing down on moving objects. My idea is: Since it is meant to be impossible to go faster then the speed of light, then as something moves faster, it should become...

Homework Statement Fred's friends are in a boat. If they could travel perpendicularly to the shore, they could land at his position. However, a strong current vc is greater than the maximum vm of the motor. Find the magnitude of the angle, measured relative to the straight-across direction, at...

Homework Statement A person in a rowboat crosses a river which flows with 4.043 km/hr. The person rows with maximum velocity of 3.138 km/hr relative to the water (measured while rowing on a still lake) and heads the boat straight across the river - along a line at 90 degrees with respect to...

Can somebody please explain for me ??

I've just started getting interested in physics and I am only a few (basic) books deep but there is something that has been distracting me that I can't come to a logical conclusion about. I assume this means there is a flaw in my basic understanding and wish to fix it asap. Here goes. I am...

Ship A is located at 4 km north and 2.5 km east of ship B. Ship A has a velocity of 22 km/h toward the south, and ship B has a velocity of 40 km/h in a direction 37 degrees north of east. (a) What is the velocity of A relative to B in unit-vector notation with i toward the east? (b) Write an...

Homework Statement A woman walks due west on the deck of a ship at 3 mi/h. The ship is moving north at a speed of 23 mi/h. Find the speed and direction of the woman relative to the surface of the water. (Round your answers to one decimal place.) Homework Equations The Attempt at a...

------------------------------------------------------------------------- SUBJECT There are various forms of energy; some are potential while others are kinetic. An object or particle can have its energy change when work is performed upon it. Likewise, it may loss some of its energy when...

i constantly feel that Newton was right in measuring the relative velocity.einstein makes use of light which has a limitation of 300000 km/s .It seems as if because light cannot travel more than 300000 km/s we we see the other object moving at lesser speed. to confirm that in relative velocity...

Homework Statement I attached the picture on the bottom (correction on the picture 30 degrees ---> 35 degrees sorry about that) Vpa: 600 km/h Vag:100 km/h and the question is to find the angle theta Homework Equations The Attempt at a Solution So I tried using Pythagorean theory by setting...

Im reading a page out of Griffiths about 2 guys holding a wire loop on a railroad car and then traveling through a B field on the track. As the guys travel at a speed v through the B field the electrons will start to move in the conductor. If we view it from the point of the the B field...

In a calculation I am getting relative humidity more than 100%. What does it suggests? I know this means liquid water is also present in addition to saturated vapour. How should I calculate liquid water content then? Do I have to calculate activity first? Also what happens when I am considering...

I'm not exactly sure how to prove or disprove this statement. Just by looking at the c, I'd say it's not true, but I'm not sure how to show it either way. If (a,b) = 1 and (a,c) = 1, then (ac,b) = 1. http://i111.photobucket.com/albums/n149/camarolt4z28/IMG_20110719_192439-1.jpg?t=1311127377

Homework Statement A particle of mass M is on a wedge of mass 2M. The wedge is smooth, and is inclined at 30* to the horizontal. The system is released from rest. Find the acceleration of the wedge, and find the acceleration of the particle relative to the wedge.Homework Equations F=ma The...

There are two points on the 2D rectangular coordinate system, namely P and M. Their positions are function of time and are: Position \, of \, P: \, (p_x(t), \, p_y(t)) Position \, of \, M: \, (m_x(t), \, m_y(t)) Distance between them is: R(t) \, = \, \sqrt{(p_x - m_x)^2 \, + \, (p_y -...