0
votes
0answers
18 views
system of tubed colliders and desired direction of movement
Imagine tube with mass M and inside it an object with mass M2 that we can force into direction x or -x. Let us say that desired direction is x. Collision between the wall at the end of the tube and ...
0
votes
1answer
35 views
Question on static friction [closed]
This is the question, and the answer is given as 2).
Now my basic doubt is, are they asking us the direction of the total contact force on the object by the floor? Or, are they asking the direction ...
1
vote
1answer
51 views
Mechanics question (a block on top of a block)
This question is very similar to this one here.
A block of mass $m_1$ is placed on another block of mass $m_2$ lying on a smooth horizontal surface.
The coefficient of friction (static and ...
0
votes
1answer
39 views
In Newtonian pressure, what type of function is force?
This is pressure in Newtonian mechanics:
$$P=\frac {dF}{dA}.$$
What does this mean?
(Doesn't it mean that force is a function of area?)
What type of function is force?
6
votes
2answers
119 views
Confusion with derivation of fictitious forces
I read the mathematical derivation of fictitious forces on Wikipedia and I'm having trouble understanding it. I went on a few other sites looking for a better derivation, but they're all basically the ...
0
votes
1answer
125 views
Tension in a massless string around a pulley
A pulley having some mass has a massless string around it,with two unequal masses at the end of the string .Sufficient friction is present between pulley and the string such that the string does not ...
15
votes
4answers
405 views
+50
Why do whips hurt so much?
What exactly is the mechanism that makes a whip deliver such a strong impact? Elasticity, torque, or pressure? Just hitting something with a plank doesn't deal nearly as much damage. What's the ...
-3
votes
0answers
31 views
Block over block Problem [closed]
There are two blocks one over the other , both on ground , masses are 2 kg for top one and 5 kg for bottom one , coefficient of friction between both is 0.8 and between lower one and ground is 0.2 . ...
2
votes
1answer
103 views
Is any work done when I walk?
I am trying to figure out the amount of work done when I walk X miles or for X minutes. So I got Work=Force x Distance and Force=Mass x Acceleration and Acceleration=(change in velocity)/time. I am ...
-4
votes
0answers
29 views
Find amount of force to move a 18 kg mass 0.1 seconds [closed]
Force is coming from two pistons pushing at 45 degrees applied to two adjacent corners of a square (0.6 m x 0.6 m) rigid plane. Mass of the plane is 18 kg. Piston stroke is 20 cm, piston bore is 40 ...
2
votes
1answer
70 views
Understanding Kepler's problem
I wanted to know a few things about elliptical motion, that I do not understand so far.
Let's imagine that we have an attractive gravitational two body problem where both bodies carry out elliptical ...
1
vote
4answers
63 views
Action Reaction when I pushing a trolley?
I tried to explain how those force work but I can hardly figure it out.
I exerted a force on the trolley and there will be a force on trolley on me as well. This is the newton's third law. But why the ...
1
vote
1answer
69 views
A block, a string and Newton's third law
So this is a general force diagram of the system shown. My question is, according to the third law, if the block is exerting a force of magnitude mg on the thread in the down direction, then the ...
0
votes
4answers
79 views
How can acceleration $a$ be zero when applied force $F$ is non-zero?
An object is at rest and stays at rest, but an attached rope pulls with increasing force. What is the acceleration?
The correct solution is that acceleration is constant and 0. Obviously $a= dv/dt ...
-1
votes
1answer
51 views
What is the minimum wrap around angles of belt, timing belt and chain? [closed]
I read a website which said the minimum wrap around angle for belt on pulley is 120 degrees, However, it doesn't say whether it is belt or timing belt. Also I want to find the minimum wrap around ...
-2
votes
1answer
61 views
Question on friction [closed]
Please look at the figure carefully. The question is written, and one has to match the two columns 1 and 2 given under "choices and explanation". Please tell me if I am really wrong, i.e. would you ...
0
votes
0answers
24 views
Force being applied to an object [closed]
I am working on a project and I do not have a clue about Physics. I have a 3400lb,1542kg object traveling at 210mph. When it is stopped by another object that is not in motion, what is the force of ...
8
votes
3answers
207 views
Where does the extra equation come from to determine the forces from an object on a table?
I have a question about basic statics but somehow I cannot manage to find the answer on my own (btw, this is not a homework. It's been so many years since school for me...).
The problem is very ...
3
votes
1answer
71 views
Why does this screwdriver roll in a curved trajectory?
I am trying my level best to give this screwdriver a horizontal push only, but it is going in a circular path. I thought of uneven friction due to non-uniform normal reaction...what do you think? I ...
2
votes
2answers
72 views
Intuition contradicting answer for calculating pressure
I have a cylindrical container say of some base area $A$. The atmospheric pressure is $P_0$. The cylinder is moved at an acceleration $a$ horizontally right. I need to find which base would have to ...
1
vote
2answers
63 views
Momentum, Impulse and Newton's Second Law of Motion
Newton formulated his Second Law as such:
$$\sum{\vec{F}} = \frac{\delta \vec{p}}{\delta t}$$
and of course, $\vec{p} = m \vec{v}$.
Why is it that if the net force $\sum \vec{F}$ is constant (which ...
5
votes
2answers
91 views
How can a car's engine move the car?
Newton's First Law of Motion states that an object at rest or uniform motion tends to stay in that state of motion unless an unbalanced, external force acts on it.
Say if I were in a car and I push ...
-1
votes
1answer
41 views
If An Object Explodes With A Force, What Force Are Fragments Given?
So let's say for example I have an object with 5kg of mass.
It explodes with a force of 500N.
The object fragments into four fragments: a 0.5kg, a 1kg, a 1.5kg and a 2kg object.
What force does ...
0
votes
1answer
50 views
Another Inclined plane question
I did the FBD, and I found too many variables which are not eliminating...Moreover, I believe this question is based on kinetic and static friction. But, $\mu$ here is ambiguously defined...How Do I ...
-1
votes
1answer
64 views
Comparing Static Frictions
In this figure, which of the static frictional forces will be more?
My aim isn't to solve this particular problem but to learn how is static friction distributed . Since each of the rough-surfaces ...
0
votes
2answers
78 views
Massless string Paradox
If we introduce the notion of a massless string to denote the fact that net force on a massless string will always be $0$, since it is massless . How can these massless strings ever accelerate when ...
-1
votes
1answer
48 views
A theoretical problem on Mechanics [closed]
Two particles with masses $m_1$ and $m_2$ are moving in 3D space with some Cartesian coordinate system. There are known the laws of motion of these particles, i.e. the position vectors $\vec{r_1}(t)$ ...
0
votes
1answer
60 views
Why body starts moving when force is applied? [duplicate]
The recent question by m.buettner regarding self-inductance and its resistance to EMF Faraday's law - does the induced current's magnetic field affect the change in flux?, recalled me the ...
1
vote
0answers
50 views
Does the slinky base stay perfectly level during the initial free fall [duplicate]
In this related question:
Slinky base does not immediately fall due to gravity
It is observed that the base does not fall immediately.
Obviously the center of mass is in free fall, and the tension ...
1
vote
2answers
65 views
Clarification regarding Newton's Third Law of Motion and why movement is possible [duplicate]
Newton's third law states that to every action, there is an equal and opposite reaction.
If that's the case, then how do things move at all? Shouldn't all applied forces be canceled by the equal and ...
0
votes
3answers
112 views
Man in elevator, holding it, on a scale
This is the scenario where my mass is $60 kg$, the mass of the elevator is $30kg$, and due to a malfunction, I have to hold myself and the elevator at rest. The question is, if there is a weighing ...
1
vote
1answer
93 views
Given a potential energy function, find expression of the force of a particle?
This comes from an AP review packet. I'm given a potential energy functon, $$U(r)=br^{-3/2} + c,$$ where $b$ and $c$ are constants, and need to find the expression for the force on the particle.
...
0
votes
1answer
91 views
Problem about moments and equilibrium. [closed]
A plank is on top of 2 branches. It is in contact at 2 points, A and B. The plank is 90 cm long. A is on the left of B. A is 15 cm from the left end of the plank. B is 20 cm from the right end of the ...
0
votes
1answer
96 views
Energy needed to lift and bring down an object
A mass of 0.5 Kg needs to be moved from point A to another point (B) which is 1 meters above point A. The time for this movement should be 0.2 seconds, then the mass is kept at position B for another ...
0
votes
3answers
148 views
Why does a rod rotate?
I'm a physics tutor tutoring High School students. A question confused me a lot.
Question is:
Suppose a mass less rod length $l$ has a particle of mass $m$ attached at its end and the rod is ...
2
votes
1answer
82 views
Convert a 200mm linear stroke into 90 degrees motion
Can anyone help me Convert a 200 mm linear stroke into 90 degrees motion with as much mechanical advantage as possible or into two 90 degrees motions with as much mechanical advantage as possible?
...
8
votes
2answers
290 views
Is acceleration an average?
Background
I'm new to physics and math. I stopped studying both of them in high-school, and I wish I hadn't. I'm pursuing study in both topics for personal interest. Today, I'm learning about ...
1
vote
2answers
66 views
Forces on a particle moving in a vertical circle
In the diagrma, a particle (A, mass 0.6kg) is moving in a vertical circle. The question is: When it gets to the lowest point, what is the tension in the light rod that is between the center of the ...
0
votes
1answer
38 views
Find the bending moment of a pole attached to a moving block
I'm having trouble with the following problem.
What I've done so far:
x-y is the usual coordinate system.
$a=\frac{F}{m}=\frac{800}{60}$ and the y component of this is $a_y=a\sin{60^\circ}$.
To ...
3
votes
3answers
147 views
Non-SHM oscillatory motion
How to solve these kind of questions , where $|F| \propto x^2$?
How to find time period and velocity type related things to the oscillatory motion?
...
-1
votes
3answers
138 views
What needs to be integrated to solve this problem?
An object is placed on a frictionless table with its one end attached to a cord which is connected to a pulley and the tension is maintained constant at 25 N. what is the change in kinetic energy ...
1
vote
3answers
178 views
Is the tension in both ends the same (on a massed string)?
If two blocks lay on a table and I pull the second block, as shown in the picture below. Is the tension in both ends of the string the same? (The string has a mass)
1
vote
2answers
104 views
Accelerating an elevator
A person is standing on a weighing scale in an elevator in upward acceleration.
Let $N$ be normal reaction force exerted by the weighing scale to the person (upward).
It is known that the person ...
2
votes
1answer
110 views
rate of change of spring potential energy $\frac{dU}{dt}$
Suppose we have a setup like this. In orange are two wooden sticks sort of things, and they are attached to the block of mass $m$(as usual) at a joint which is hinge type something. A similar ...
1
vote
2answers
57 views
effect of vertical collision on kinetic friction and subsequent change in horizontal velocity
Suppose somehow a block of mass $m$ is moving on ground, and the coefficient of kinetic friction between the block and the block is $\mu_k$. If I drop a tennis ball(of same mass) on it from a ...
2
votes
1answer
126 views
Is there a geometrical way to obtain a relationship between these vectors?
Suppose we have a setup like this. Here $a_1,a_2,b_1,b_2$ are acceleration magnitudes($b_1,b_2$ being relative) and $P,Q,R,S$ are not pulley/blocks but are points on the rope. If I use a geometrical ...
2
votes
2answers
131 views
Movement of man and ladder and their center of mass
Suppose there is a massless frictionless pulley.
A rope over it carries a mass $M$ and on other side carries a ladder of mass $(M-m)$ and a man on that ladder, of mass $m$. Now the man starts ...
0
votes
0answers
48 views
Does distance increase force at impact? [closed]
If a car that weights 1800 KG is traveling at 2.235 ms would it with greater force and 25 feet than 10 feet?
My calculations say it would be the same if the road was level and the same surface ...
1
vote
1answer
137 views
Work done by friction
Suppose we have a block of mass $M$ and we are moving it up a curve, very slowly ($a=0$). The surface is not smooth, and coefficient of friction is $\mu=\mu_s=\mu_k$.
To move the block we apply a ...
1
vote
1answer
157 views
Newton's Third Law of Motion
I want to start off by saying that I've looked around for other explanations, but I've not really found any satisfying ones. My question is basically the whole "Why can anything move at all?" ...
