If a horse pulls the carriage, the carriage should pull the horse with equal force (Newton's third law), then how does the whole system move? I drew the free body diagram but not yet figured what makes the whole thing move. Please give me an explanation.
4352
Given Newton's third law, why is there motion at all? Should not all forces even themselves out, so nothing moves at all? When I push a table using my finger, the table applies the same force onto my finger like my finger does on the table just with an opposing direction, nothing happens except that I feel the opposing force. But why can I push a box on a table by applying force ($F=ma$) on one side, obviously outbalancing the force the box has on my finger and at the same time outbalancing the friction the box has on the table? I obviously have the greater mass and acceleration as for example the matchbox on the table and thusly I can move it, but shouldn't the third law prevent that from even happening? Shouldn't the matchbox just accommodate to said force and applying the same force to me in opposing direction?
25420
When two bodies, free of movement, are linked by a physical constraint (a maximum distance between them) how do their masses and velocities influence each other? Which formula with theses parameters gives the force applied by one of the two on the other?  For example : I have two box (grey and red) that are next to each other attached by a rope of maximum length L, the grey one jump following the yellow curve C and i'm trying to get the equation to find the force applied to the red box when the distance between the boxes reach L. V is the velocity when the gray box reach the red circle. It would probably split into the radial force and the tangential force depending on the angle. I guess the answer would probably work for every position on the red circle.  I tried to read about pendulum but there was only the gravity taken into consideration, and it kinda felt like the tension was vertical. There might be an answer for me in one ticket but i just couldn't find it.
53167
While DMing my session today, I encountered a situation I wasn't sure how to answer. The PCs were attacked by a werewolf and decided to flee onto their nearby horses. Two of them were already mounted and two of them were on foot. One player on the ground (a wizard) attempted to cast a spell on the werewolf and failed. He then moved closer to the mounts but couldn't make it with his speed. After a few turns it was the barbarian's turn. The barbarian wanted to drag the wizard with him and plop the wizard onto a horse and then mount with his remaining movement speed.  I wasn't sure quite how to handle it, so I made a compromise. I allowed the barbarian to drag the wizard. However, because the rules specifically state that it takes half of a character's movement to mount, I wouldn't allow the barbarian to force the wizard to mount. However, if the barbarian wanted to, he could mount the horse himself as he had enough remaining movement.  The reason I allowed the barbarian to drag the wizard is because of the lifting, dragging, and pushing rules in chapter 7 of the Player's Handbook. The barbarian had more than enough strength to push our tiny, lightweight wizard around.  I'm not really sure if I handled it right at all. I'm not entirely sure that those rules apply to living beings, especially living beings that can move. I would really appreciate some advice on whether or not players can drag other players after their (the player who is being dragged) turn is over or if players can drag other players at all. If I recall correctly, I believe the wizard still had about 5' of movement left, if it makes a difference.
251
My father explained to me how rockets work and he told me that Newton's Third Law of motion worked here. I asked him why it works and he didn't answer. I have wasted over a week thinking about this problem and now I am giving up. Can anyone explain why Newton's Third Law works? For reference, Newton's third law:  To every action there is always opposed an equal reaction: or the mutual actions of two bodies upon each other are always equal, and directed to contrary parts.
50650
When the train accelerates, the bob would also accelerate with the same magnitude and direction as the train. From the free body diagram, only tension and weight are exerted on the bob. I understand how to relate the "horizontal component" of the tension to the acceleration of the bob. It moves "backward" and in fact its vertical position is different from when the train is not accelerating.  I am not sure whether inertia could explain this situation. What is the force moving it backward/ lifting with the height?
57608
Newtons three laws of motion appears to apply only for linear motion:   An object remains at rest or moves in a straight line at uniform velocity unless a force is applied.  Force is mass times acceleration.  Every action causes an equal and opposite reaction.    Is there a rotational equivalence? For example:  1'. Every body rotates around a fixed axis at uniform angular velocity unless a torque is applied 2'. Torque is Moment of Inertia times angular acceleration 3'. When one body exerts a torque on another; there is an equal and opposite torque applied on the first body by the second.  First are these actually correct; if not, what are the correct equivalence; and who formulated them?
85977
The tension of a rope in a tug of war with unequal forces is equal to the least force on the rope. Am I right? (If group A pulls the wire with 20 newton leftwards and the group B pulls with 30 newton. I expect that the tension is 20 newton.)   But the tension on the rope pulling a mass vertically upward is said to be equal to $mg+ma$.( where $m$ is the mass of the object being pulled, $a$ is the acceleration of the object)  How come the same situations bearing different answers?
15882
As a physics newbie I'm trying to get a grip on basic orbital mechanics. I think I'm beginning to get grasp on how bodies interact with each other. When a body approaches another body it accelerates due to gravity. It can reach a point where its velocity is high enough to keep falling but also keep missing the object it is falling towards. What keeps it from accelerating (because of gravity) and eventually reaching escape velocity? I feel like I'm either looking at things the wrong way or I have the entire thing wrong.
18610
In my textbook, the definition of tension was given that  is the reactive force which exists when string is being stretched at its both end. After it there was a case given that to calculate acceleration and tension produced in string while it's attached with different masses at both its ends and passed over a frictionless pulley. First body is being hung and second is placed over horizontal frictionless surface with relatively smaller mass. It is given in my book that there are three forces acting on the body placed on horizontal smooth surface viz., Weight of body, the reaction force to weight and tension in string pulling body towards pulley's wheel. How can there be tension in string according to the definition given my book however there is no acting force (pulling force) on the body that pulls it away from wheel.  There are different definitions for tension. The one in our book is creating problem however second one, that is, " tension describes the pulling force exerted by each end of a string, cable, chain, or similar one-dimensional continuous object " is al right.  Since acceleration is lowered due to Tension then acceleration produced in the body must be given by, $a=\frac{Net-Force}{m}$ $=&gt;$ $a=\frac{m_1g-T}{m_1}$ since $W_1$ $&gt;$ $T$.  If tension in string is the reactive force to the weights pulling the string apart then according to Sir Isaac Newton, $W_1=W_2=T$.
109247
When drag force ($bV$) equals to object's weight (mg) then upward and downward force becomes equal. As a result the object comes to rest. If this is true, how is a body moving with constant velocity?
27801
Let's say that we have a car travelling at a constant velocity (V) on a flat plane , let's assume that it's applied force or the force applied from its engine ( Fapp ) balances the frictional force ( Ffrict ) , hence the power due to Fapp is equal to Fapp×V , now let's assume that the same car now moves up an incline with the same engine power as previously stated and at a constant velocity ...but this time it will travel at a much lower constant velocity since the force which the engine exerts is much higher now in order to balance Fparalell and Ffrict , but what I don't understand is what caused this reduction in velocity , if the engine applies an equal force to that of the counteracting forces shouldn't that mean that there is no net force hence no change in velocity ,also if p=FV and if we now apply a greater force for the same velocity V why does the power increase , I know the answer can be simply explained using mathematics but my intuition says that power is the rate at which kinetic energy is transferred to a particle , so why would a greater force at the same constant velocity mean that you are transferring a greater amount of KE per unit time ?
21370
When a car's engine injects fuel into the cylinder chambers, the reaction creates a force that generates rotational momentum to the shaft and over the transmission, it translates that power to the wheels, right?  But, something's bothering me, how does the car actually move, is it dependent on the force of friction? Wheels have a contact with the road in one exact point and when the drive gets to rotate them, a force is exerted on the road in the direction of movement and there is friction that is counteracting it.  Is the key to get a car properly moving to have the drive force equal or less than the force of friction to keep that point locked to the ground and use the rolling of the wheel for translational displacement ie. moving forward? If it's bigger than the force of friction, that would cause the wheels to spin in place?  Am I completely off or am I getting something right? If there's a knowledgeable person on this topic, I'd greatly appreciate some insight, perhaps even a bigger response with some basic vehicle physics.
98902
In whichever angle an object is thrown at a surface, the surface always exert force normal to it. But why? According to Newton's third law, if an object hits a surface at an angle, the reaction force provided by the surface must be equal and opposite to the applied force by the object. But why  does the surface always exert force normal to it?
70536
A pulley fixed to a rigid support carries a rope whose one end is tied to a ladder and a man and the other end to the counterweight of mass $M$. The man of mass $m$ climbs up a distance of $h$ with respect to the ladder and then stops. If the mass of the rope and the friction in the pulley axle are negligible find the displacement of the center of mass of the system.   My question is that the net external force on the system is 0 then why is there any displacement of centre of mass?
90265
I've got a lot of question about normal force. First, what causes normal force. Next, how do the object know how much normal force to exert. Lastly, how is this not an application of Newton 3rd law. Imagine a book on a table. The book is exerting a downward force on the table(weight), the table is exerting a normal force on the book(upwards) . People keep saying that they act on the same objecr, the book, but the book's weight is acting on the table, so why is this not Newton 3rd law
16675
I heard that a magnetic field only creates a force on a moving charge, not a stationary one. However, what if the solenoid containing the magnetic field was moving through a stationary charge. Would that create a similar force? Thanks!
70557
I am a bit confused about the relation between rolling resistance and static friction.   I have often heard that it is the static friction that lets the wheel roll. Consider the following two cases:  a) A tire of a car of mass $m$ moving with positive acceleration $a$ on a street b) A wheel of a moving wagon (of mass $m$) which is pulled by a string (with force $F_\mathrm{string}$).    How do the free body diagrams look like? (including static friction, rolling friction and friction forces at the axis) What is the resulting force accelerating the center of mass of the wheel in case b) (in dependence of the frictional coefficients and $m$)