Newtonian mechanics covers the discussion of the movement of classical bodies under the influence of forces by making use of Newton’s three laws. For more general discussion of energy, momentum conservation etc., use classical-mechanics, for Newton’s description of gravity, use newtonian-gravity.

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Elastic collision / relative velocity problem

I'm having some trouble with a homework exercise and I'd really appreciate some help! I've done the first part correctly (according to the solution sheet), but I can't seem to get the second part ...
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1answer
19 views

A couple of questions regarding work to velocity exchange

I was tasked to express the velocity of the cube of mass $m$ at point B using the constants given in the picture below. Friction could be ignored, and the cube could be presumed to reach B with the ...
4
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2answers
28 views

Acceleration of a car on Earth and on the Moon

Suppposing the same enviroment conditions and without considering the air friction a car at the start of a race would have a greater acceleration on Earth or on the Moon, or would the accelerations be ...
3
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0answers
49 views

Uniqueness of solution in newtonian mechanics

Recently I came across the problem of Norton's dome. I thought of two questions, for which I found no answer. Does there exist a newtonian initial value problem, where the total force on each body ...
0
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1answer
21 views

Find the magnitude of the resultant force which these engines exert on the rocket?

A rocket fires two engines simultaneously. One produces a thrust of 760N directly forward while the other gives a thrust of 484N at an angle 34.0 degrees above the forward direction. What is the ...
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0answers
42 views

Why is there not always a force in the direction of motion?

This was a question on a physics competition. A girl throws a teddy bear straight up. Consider the motion of the bear only after it has left the girl’s hand but before it touches the ground, and ...
0
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0answers
30 views

A body thrown upwards with some external force [on hold]

A ball of mass of $1Kg$ is held in hand. The moment it is released from hand, without any delay it is hit by an external force of $100N$ in upwards direction. How high will the body go ? If we ...
-1
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0answers
27 views

Freely falling body applied some external force [on hold]

A body of mass $10kg$ is thrown upwards with initial velocity = $10m/s$. Then it moves up and falls back down at the same point, after which an external force of $10N$ is applied in the upward ...
1
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3answers
172 views

Where Potential increase gets it's energy from?

Imagine there are two particles: A,B; of which, we observe A to be stationary, while B is moving towards A at velocity v. A,B has same mass; and they are charged both positive. B has a potential wrt ...
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3answers
32 views

When a person bends forward, does normal reation force change as a component of his weight is applied in torque?

My thoughts :i read that normal reaction is equal to the weight of the person in the case above as the effective vertical force in the system is zero.but im confused cuz a component of the weight is ...
0
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2answers
32 views

Conservation of energy in vertical circular motion

Books usually use conservation of energy to solve problems in vertical circular motion. But, principle of conservation of energy for one particle is, If all the $n$ forces $\vec F_i ...
0
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0answers
40 views

Can the linear momentum of a system be constant, even though its centre accelerates?

My instructor says if the velocity of center or mass is constant, it means that the linear momentum of a body is conserved. So if no external force acts on a body, there is no change in the linear ...
0
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1answer
87 views

Euler's laws - derivation

It looks simple and maybe is easy, but I don't get it. How to obtain the second equality from the first one below? Source: http://emweb.unl.edu/NEGAHBAN/EM373/note19/note19.htm They took ...
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1answer
38 views

Action - Reaction?

I got to know that when a book is kept on a table. Earth attracts it due to Gravitational force. The book responds by attracting the earth with same force. (An action-reaction pair) The book is kept ...
-2
votes
0answers
27 views

Downforce formula [on hold]

I need a formula force calcuating the down force generated by a NASCAR. I have done research and found some answers on google but i don't know what the formulas mean. So i was wondering if any body ...
2
votes
3answers
58 views

If I push my hands against each other, why does the stronger one move the weaker one if the forces should be equal and opposite [duplicate]

If I were pushing my hands against each other, the stronger arm will move the weaker arm, but if all forces have an equal and opposite reaction, why does the weaker one move?
0
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3answers
33 views

2 airplanes same size and shap different mass

2 identical balls of different mass dropped from same height reach the ground at the same time due to the acceleration of gravity being constant. If I understand correctly the ball with more mass ...
4
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2answers
1k views

How do I experience Earth's movement?

We are told that Earth is spinning on its axis at 1037 mph— something that we don't usually feel because of the environment that moves with us as well. Is there any experiment with which we can know ...
0
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2answers
46 views

What is relationship between linear and angular momentum?

I'm confused about imparting momentum to a sphere, which causes it to rotate without slipping. Does the momentum applied go: only to the rotational motion and the linear is a consequence of the ...
1
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4answers
44 views

how is a pendulum clock's time and the time period of the pendulum in it related? [on hold]

I'm working out how much time a pendulum clock will gain or loose due to change of the length of the pendulum due to temperature. so far I've got, new time period, $$T_2=T_1(1+\frac12\alpha\Delta T)$$ ...
2
votes
2answers
109 views

Fired a bullet upwards, can it fall down and kill me?

I know that if something is thrown up with a velocity v, it comes down with the same velocity as long as its motion faces no resistance. So is it possible for me to fire a bullet and be killed if it ...
1
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1answer
47 views

What makes cart with a moving object in it gain speed (no friction anywhere)?

I would like to understand what makes the cart below the moving object move. There is no friction between any of the objects. The cart is moving therefore there is force applied to it. The only force ...
2
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2answers
51 views

Why dont you take derivative of force in definition of power ? P=F.v

The derivative of work is $\bf F\cdot v .$ $$P(t)= \frac{\mathrm dW}{\mathrm dt}= \mathbf{F\cdot v}=-\frac{\mathrm dU}{\mathrm dt}\;.$$ But why not $$(\mathrm d(\mathbf F)/\mathrm dx)\cdot \mathbf x ...
0
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2answers
41 views

Work-Energy Problem

A wire, which passes through the hole in a small bead, is bent in the form of quarter of a circle. The wire is fixed vertically on ground as shown in the figure. The bead is released from near the top ...
-1
votes
1answer
45 views

If a car is moving through space and you place an object in it, what would happen to the car's velocity? [on hold]

If a car is moving through space and you place an object in it, what would happen to the car's velocity?
-1
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0answers
39 views

Find Time it Takes For an Object in Free Fall To Hit Ground With Given Gravity [on hold]

Sorry if this seems like a simple question. I'm not that good with physics but I'm willing to learn! So my question is, how can I find the time it takes for an object at "h" height to hit the ground ...
3
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0answers
27 views

The physics of an anvil [on hold]

I am trying to understand how an anvil might best be made. An anvil requires two essential characteristics: enough hardness to not be deformed under the blows of the hammer, but as little rebound and ...
1
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0answers
40 views

What is the path taken by a “cable car”?

A well known result in variational calculus & Lagrangian Mechanics is the solution to the "brachistochrone" problem, where it is found the path connecting two points, A & B such that the time ...
-6
votes
0answers
35 views

m1v(initial) +m2v (initial) = m1v (final) +m2v(final) [on hold]

Perfectly elastic collisions. Imagine two billiard ball on the table. Ball A has a mass of 2 kilograms and the ball B has a mass of 3 kilograms. the initial velocity of ball A is 9 meters per second ...
0
votes
1answer
24 views

Massless rope in a pulley pulled by a person

A massless rope passes through a pulley. On each end of the pulley there is a different mass (object). A person grips one of the masses and thus the system comes to equilibrium. How would you ...
-1
votes
2answers
85 views

Conservation of momentum and conservation of energy

I had the impression that conservation of momentum is valid only when we consider no loss of kinetic energy into heat etc. My tutor says that even if we have loss of kinetic energy as heat in a ...
0
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0answers
46 views

What does representing position as a function of frequency mean? [on hold]

I am doing an introductory course in quantum physics. A part of the magical paper of Heisenberg says, "For a state characterized by the label $n$, the fundamental frequency $v(n)$, and the ...
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4answers
167 views
+50

What will be final velocity of three charges $q$, $q$, $2q$?

What will be final velocity of three charges q, q and 2q kept along an eqilateral triangle of side r at infinite distance. All three masses are equal. I tried to conserve Total Energy ...
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1answer
36 views

a problem on circular motion [on hold]

Question:A cyclist is riding with a speed of $7.5$ m/s. As he approaches a circular turn on the road of radius $80m$, he applies brakes and reduces his speed at the constant rate of $0.50$ m/s every ...
-4
votes
0answers
50 views

Science question [closed]

imagine two billard balls on a pool table A ball has a mass of 2 kilograms and ball B has a mass of 3 kilograms. the initial velocity of ball A is 9 meters per second to the right and initial velocity ...
0
votes
3answers
43 views

Direction of velocity and acceleration for a pendulum [duplicate]

The image below shows the direction between acceleration and velocity change with time. But it seems to me that the direction is not opposite. Can you please see and tell if this is correct?
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2answers
36 views

Objects and forces: air resistance

A force always works between two objects. When we are talking about air resistance acting on a skydiver for example, would air be considered the second objects besides the skydiver?
0
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3answers
46 views

Conditions for the tension to vary in the rope

What are the conditions for the tension to vary in the rope. I have read below conditions 1. rope has to have some mass 2. rope is accelerating I get the 1st ...
-4
votes
0answers
34 views

Calculate the loss of kinectic energy during this collision [closed]

Calculate the loss of kinectic energy of a car with mass 1000kg moving at 10m.s which collide with a stationary truck of mass of 9000kg
1
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2answers
30 views

Tension in the string

In the following diagram, what's the force that's acting on m, the Tension in the string? There is no friction between M and the ground but there is between m and M and I need to find the minimum ...
0
votes
3answers
77 views

What is the difference between these two springs?

I know that the stifness of the following springs are different. But how to find their spring constant? I think that one has the tension force is fully transmitted along the solid (but is it ...
-2
votes
0answers
30 views

How to be an active undergraduate physics student? [closed]

How could we become an active physics guy in freshman year?I mean, is it enough to read only about CM.And be good at that.And be unknown to modern physics.Or,shall we know physics modern information ...
1
vote
1answer
64 views

Does this count as a proper derivation of the formula for work and kinetic energy? [on hold]

$v_{av}$ = average velocity, $d$= distance, $a$ = acceleration, $m$ = mass Given: $$v_{av}*t=d$$ $$t=\frac{v_f-v_i}{a}$$ $$v_{av}=\frac{v_f+v_i}{2}$$ Then: $$\frac{v_f+v_i}{2}*\frac{v_f-v_i}{a}=d$$ ...
1
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0answers
51 views

Eigenfrequencies of a truss

I want to calculate the eigenfrequencies of a 3D truss using the finite element method. The beams should be modelled as Timoshenko beams and I want to use arbitrary shape functions. I know how ...
0
votes
3answers
30 views

Effect of internal force on the weight of an object

A man is holding a closed cage on the palm of his hand with a bird in it. When the bird flies with an upward acceleration inside the cage, it feels heavier. But the force due to the bird in the cage ...
-2
votes
1answer
71 views

Boeing 737 Homework Problem [closed]

I have done the above problem, but have come out with a rather large surface area. Could someone point out my mistake(s)? Given/Assumptions: I assume $\sum F_y=0$ because it's level and straight. ...
1
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0answers
23 views

What forces act on a caravan being towed by a car? [closed]

What forces act on a caravan that is being towed by a car? How does this compare to a simple car travelling at a constant speed?
0
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1answer
46 views

Relationship $v_A^2-v_B^2=2a_t\Delta s $ for motion with constant tangential acceleration [closed]

I can not understand a relationship in the general motion in the plane. I am considering a point, which follows a curved trajectory. Indicate A and B two different position of the trajectory and $v_A$ ...
3
votes
1answer
43 views

Particle sliding down frictionless hemisphere on frictionless surface

http://web.physics.harvard.edu/uploads/files/undergrad/probweek/prob87.pdf http://web.physics.harvard.edu/uploads/files/undergrad/probweek/sol87.pdf The problem and the suggested solution are in the ...
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0answers
113 views

To prove uniqueness of the rotation tensor associated with rotation of a rigid body

Suppose there are $N$ particles embedded in a rigid body which undergoes some random rotation such that: $$ \overline{\overline {R}}_{ij} \otimes \vec{a}_{ij} = \vec{b}_{ij}$$ where, $i$ and ...