All Questions
Tagged with relative-motion homework-and-exercises
128
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Question regarding friction acting on a disk on a conveyor belt [closed]
I have the following problem on which i am working
A horizontal conveyor belt is running at a constant speed of $v_b = 3.0\hspace{1mm}m/s$.
A small disc enter the belt moving horizontally with a ...
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1
answer
35
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How to calculate the relative speed when three bodies are involved? [closed]
Two trains A and B start from a station and move in parallel tracks with velocities 40 kmph and 60 kmph respectively. A man sitting in train A. watches a lady who walks inside the train B at a speed ...
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1
answer
78
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Calculating relative velocity: What am I doing wrong? [closed]
There are two objects A and B. Points P1, P2, P3 are in the same line, and P2 is exactly at the middle of P1 and P3
Suppose B is moving at constant velocity along the line P1 to P3. Thus, time taken ...
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1
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Wording of Relative Velocity problems [closed]
I've been doing some relative velocity problems. The three main types I do are to do with cars, boats/rivers and planes/crosswind.
I'm fine with cars as the wording is pretty straightforward - it is ...
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Velocity of Separation and Relative Velocity
I have some problems in understanding a concept, which has been used in the problem in the picture:
I don't understand what are we actually using to solve this question. Are we using relative ...
1
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1
answer
60
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Simple classical mechanics problem to compute minimum distance attained between two ships moving with constant velocity
I have been reading the book "A Course in Classical Physics 1 - Mechanics" by Alessandro Bettini. I have reached a problem in the first chapter that I am having trouble with.
The problem ...
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1
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44
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Is the relative velocity between these two particles increasing or decreasing? [closed]
The displacement time equations of two particles are:
$$s_1 = 2t-4t^2$$
$$s_2 = -2t + 4t^2$$
By differentiating we can find $v_1,v_2$. Subtracting them gives: $v_1-v_2 = 4-16t$
Clearly, this ...
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119
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Wind and sound waves [closed]
The official answer is C.
Why not A? If I add a horizontal component of velocity towards left, why would the path become curved?
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1
answer
95
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For an airplane moving north from some latitude (say $30^{\circ}N$), why does rotation of the Earth cause an increase in apparent drag?
I'm not able to understand the answer to this example:
Example 10 from the Curtis Orbital Mechanics text book :
An airplane of mass $70 000\ \mathrm{ kg}$ is traveling due north at latitude $30^\circ$...
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1
answer
111
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Distance between two airplanes [closed]
I need help with a vector problem where my solution is different from that of my teacher. The translation of the problem reads as follows:
An air traffic controller observes two aircraft on his radar ...
6
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3
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516
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Interesting answer as a range of tension in pulley-block-plane system
I want some intuitive understanding on why there will be a range in tension in the below question. (On solving we will get that the system is at rest ($a=0$) and since its starts from rest the blocks ...
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1
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Relative Circular Motion [duplicate]
Four particles $P_1, P_2,P_3,P_4$ are moving in a plane. At $t=0$, they are at the four corners of a square $ABCD$ of edge length $l$. Each of the particles has a constant speed $v$. The velocity of $...
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1
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Velocity of a swimmer relative to the Earth [closed]
Julia can swim 0.34 m/s in still water. She swims directly east across a river that is 180 m wide and lands at a point that is 81 m north downstream. Determine Julia's velocity while swimming relative ...
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2
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What will be the minimum drift possible when a boat crosses a river? [closed]
Imagine a boat with a constant speed $v$ that has to cross a river of width $d$. Let the river flow with a constant velocity $u$. I want to know the angle at which the boat should sail in order to ...
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2
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91
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Why does these two masses not have same acceleration? [closed]
Assumptions: No friction , $m_2$=5kg and $z_1$=2kg. $z_2$ is fixed at its place.
Here, there is a mass of $5kg$ on a movable wedge of mass $2kg$. So, my question is that can we say that acceleration ...
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On a rainy day, a man is running on a hilly terrain in such a way that he is always finding the rain drops hitting him vertically
It is assumed that rainfall is uniform in the whole terrain from O to E(figure attached) When the man was at rest on stretch OA, he found the rainfall at an angle of $30^o $ with the vertical.
What ...
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1
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Why do we say the resultant vector as the relative motion in this case?
If a car A moves with acceleration $2m/s^2 $due east and car B moves $1m/s^2 $due north. What would be the acceleration of car B with respect to car A. Now , for this. The solution in my textbook is ...
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3
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133
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Question regarding relative velocity of muzzle bullet? [closed]
A police jeep is chasing with, velocity of 45 km/h a thief in another jeep moving with velocity 153 km/h. Police fires a bullet with muzzle velocity of 180 m/s. The velocity it will strike the car of ...
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Why is direction of train like this for car?
This is an image of a train and a car. T is the train moving towards - $x$ axis and C is the car moving towards $+ y$axis.
So, my teacher made a resultant velocity with $-5\hat i$ and $-20\hat j$. ...
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2
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Is this correct regarding velocity of train?
So many yellow T drawn are just different position of train at different instants.The person is standing still at all those instants at one place.
If a train is moving at 5m/s.
Then for me , can we ...
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Direction of $V_RM$ confusion
So ,please read both the questions . They have similar originate questions that I am facing difficult in.
Let us say rain is falling downwards with v = -5j and a man is moving with a velocity of 2i in ...
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2
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1
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190
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Relative speed of satellites in different orbits [closed]
The question is
"The Hubble Space Telescope is in orbit around the Earth at a height of 560km above the Earth’s surface. Take the radius and mass of the Earth to be 6.4×10^ 6m and 6.0×10^24 kg, ...
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I want to know the difference in two methods I have solved [closed]
A thief is driving away on a straight road in jeep moving with a speed of 9 m/s. A police man chases him on a motorcycle moving at a speed of 10 m/s. If the instantaneous separation of the jeep from ...
user280997
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4
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Why does the relative motion go wrong here?
Question statement:
A rocket is moving in a gravity free space with a constant acceleration of 2ms−2, along + x direction (see figure). The length of a chamber inside the rocket is 4 m. A ball is ...
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Motion of Points around a Triangle [closed]
I came across this problem in the book "Problems in General Physics by IE Irodov"-
Three points are located at the vertices of an equilateral triangle whose side equals s. They all start ...
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2
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Velocity Question from grandparent
My Grandparent asked me this question a few years ago, and I am getting around to giving him an answer, but I don't know the answer. Can anyone help?
"A pickup truck is speeding along a highway ...
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2
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286
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Change in Kinetic Energy in two different reference frames (one of them non-inertial) [duplicate]
Let's say an object of mass 10 kg is fired from a cart of mass 90 kg. The object and the cart, of total mass 100 kg were initially moving together with a speed of 10 m/s. Then, the object is fired by ...
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Why is heat energy dissipation in two intervals frame dependent?
The question asks for heat produced in the given specific conditions. It seems like an application of the work-energy theorem with friction doing work on the block and dissipating the heat in the ...
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2
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Upstream and downstream problem using relative velocity
On a river coast, there is a port; when a barge passed the port, a motor boat departed from the port to a village at the distance $S_1 = 15$ km downstream. It reached its destination after $t = 45$ ...
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1
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489
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Forces acting on a book on a moving table [closed]
I’m studying for an upcoming physics exam and one of the sample questions essentially boils down to this: a book (not clamped on) is on a table that is moving to the left. Is there a force of static ...
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1
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Problem regarding relative velocity [closed]
Train A moves north with speed 54km/h. What is the velocity of a monkey running on roof of a train A against its motion (with velocity of 18km/h with respect to A)as observed by a man standing on ...
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1
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A non-intuitive kinematics problem? [closed]
Ann is sitting on the edge of a carousel that has a radius of $6\ \mathrm{m}$ and is rotating steadily. Bob is standing still on the ground at a point that is $12\ \mathrm{m}$ from the centre of the ...
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1
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61
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Momentum conservation of a rocket [closed]
I am trying to solve a relativistic rocket equation. The rocket dumbes fuel $N$ times, in the $-x$ direction, with a mass of $\varepsilon m_0$, where $m_0$ is the rest mass of the rocket. The rocket ...
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What will be the total work done by friction on the system (man+boat)? [closed]
As I am seeing this, the man and boat will have different displacement from ground frame, so there should be a net work done by friction . The books says, total work done by friction is zero when ...
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3
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A textbook problem on vectors [closed]
I am stuck on a textbook problem on vectors (a new topic for me). The problem given in my book says:
A man can swim with a speed of 4 km/h in still water. How long does he take to cross a river 1 ...
user236322
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1
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113
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An Evil Vector Problem! [closed]
A person is walking on straight road starting with a velocity $v$, the direction of of air ,observed by him makes an angle $\alpha$ with his is direction of motion. Now during the race, he finds ...
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1
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relative acceleration of ball in a train [closed]
A boy is standing in a train with a ball in his hand. The train is having a constant acceleration equal to x m/s^2. While still in train he throws the ball with a constant velocity of 20 m/s at an ...
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1
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Free fall time after being accelerated [closed]
An elevator car whose floor-to-ceiling distance is equal to $2.7m$ starts ascending with constant acceleration $1.2 m/s^2$; $2.0 s$ after the start a bolt begins falling from the ceiling of the car. ...
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1
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Velocity of approach which changes continuously [closed]
There are two particles A and B which are moving with constant speed $v$ and $u$ such that $v$ is always directed towards B. At $t = 0$, the separation between A and B is $l$ and $u$ is perpendicular ...
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2
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Relativity: moving space shuttles [closed]
Two space shuttles $A$ and $B$ are moving in opposite directions. A person on Earth measures $v_A = 0,75 c$ and $v_B = -0,85 c$. What is the velocity of $B$ relative to $A$ (= $v_{BA}$)?
So my first ...
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Time when two particles will meet [closed]
Particle P moves with constant speed of 13m/s always aiming at O . As P starts moving , O moves with constant velocity of 5m/s towards positive y-axis. Time taken by particle P to catch O will be?
I ...
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Relative velocity of a thrown object w.r.t. ground [closed]
An old-fashioned coke bottle is thrown straight out from the right side of a car at 10 m/s. The car is moving at 80 miles per hour. What is the speed of the bottle relative to the ground (in m/s)?
I'...
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2
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What does speed of an object relative to water mean?
A swimmer swims with the velocity 1.25 m/s "relative to water". He has to swim across the river which is 150 meters wide. If his direction of velocity is perpendicular to the stream, he is taken away ...
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605
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Is this Question correct? Newtonian Motion - Relative Motion of Rain
There is a question in a textbook which states:
"A cyclist is riding north at 12km/h when it starts to rain. The rain appears to be falling towards her at an angle of 10 degrees relative to the ...
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2
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156
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Doubt on how I have applied Newton's law of motion
I have found several questions where the pseudo force is applied in the wrong direction, and I am confused whether I m correct or not. The question is something like this.
Thin threads are tightly ...
user203191
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1
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Rotationated inertial frames and Galileo Relativity
Consider then a inertial frame $S$ and another one, $S'$.
The inertial frame $S'$ is at uniform motion with respect to $S$.
Both inertial frames are the Euclidian vector spaces $\mathbb{E}^3$ equipped ...
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401
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Classical mechanics problem - relative velocity
I'm having a hard time solving this problem concerning relative motion:
A hare runs with a constant speed $u$ on a straight line. A dog chases the hare by always running straight to it with speed $...
-1
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1
answer
414
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Find velocity using integration method or relative velocity approach [closed]
In the diagram shown below, jeep moves with a speed of 60kmph and the car's velocity as observed from the moving jeep is 20kmph. we need to find the velocity of the car. I used relative velocity ...
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3
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Ship' smoke velocity?
I am studying mechanics from MIT 2.003. In HW problem "which I solved wrong" they stated that:
An important fact is that the smoke travels with the wind at the velocity of the wind
In this problem ...
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413
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Question based on relative motion in two dimension
I came across this problem in my work book.
A hunter is riding on an elephant of height $4$ $ m$ moving in straight line with uniform speed of $2$ $ m/s$. A deer running with a speed $V$ at a ...
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