Third law Definition and 371 Threads

Homework Statement Use Newton's third law to explain how a rower makes his rowing boat move forward through the water. Homework Equations no equations required The Attempt at a Solution According to Newton's third law, there is a reaction force for every action force. In this case, the...

I am not the best at drawing, I know. If A exerts a force of 200N on B, then by Newton's third law, 200N would be exerted on it. Similarly, if B exerts 100N on A, by Newton's third law, 100N would be exerted on it. Then why wouldn't both accelerate in opposite directions with accelerations equal...

If an apple hanging in the tree has only reaction upwards, then what will happen to a Newtons third law? how is it that there is no "force " downwards, but have spacetime curvature which "mimics" a force. why can't spacetime curvature be itselt a force?

Homework Statement In terms of Newton's Third Law, why is it better for 2 cars of the same mass, both going 50km/h to crash into each other than for 1 car going 100km/h to crash into a wall? Homework Equations Newton's Third Law F=ma The Attempt at a Solution I have no idea. I'm really confused

Kepler's third law states T^2=(4pi^2/GM) x r^3 for CIRCULAR orbits. My question is, in the derivation for this equation ma=GMm/r^2 why can centripetal acceleration be used to replace a at m(v^2/r)=GMm/r^2 yielding v^2/r=GM/r^2 when the orbit is not circular. Planets have elliptical orbits so why...

There is a classical thought experiment on trying to exceed the speed of light: if you push a light-year-long rod, on whose end is a button that will be pressed by the rod, wouldn't you be vastly exceeding the speed of light (which is the speed of cause & effect) by pressing the button...

Homework Statement Explain why when a person in a canoe throws a package onto the shore, the canoe moves away from the shore? Homework Equations No equations, just Newton's third law. The Attempt at a Solution I think it's because the person applies a force onto the package and the package...

let's look at force at the atomic level to understand the Newtons third law of motion. I'll use Helium atoms as an example. Now imagine we start with one atom HE2 stationary, and throw another atom HE1 at it.It is the velocity of HE1 that affects the motion of HE2 , because the system of these...

Homework Statement Emma and Caleb are playing a game. I don't know what the name is, but they put their fingers together like a hook and then pull. Caleb won. does that mean that Caleb pulls with greater force than Emma pulls him? Caleb wins. Does it mean that he pulls with greater force than...

How R^3/T^2 is a constant, or is it just the simple relationship between the distance between a planet to a star in a solar system and the period for that planet to orbit the star?

Homework Statement [/B] Three blocks move on a frictionless surface and a 42N force acts on the 3kg block. The force exerted by the 1 kg block on the 2 kg block is 14N. What is then the force exerted by the 2 kg block on the 1kg block? If it is 14N, then shouldn't the 2kg block stay in...

Hey guys, I have some confusion with Newton's Third Law. I understand that, for example, if I push against a wall the wall feels my force and the wall puts an equal force onto me. One confusion comes from the horse cart problem, or any motion problem that uncludes one object pushing another...

The Newton's third law states that the force exerted by body A on body B is equal to the force exerted by Body B on Body A . In this case, isn't the object supposed to be stationary because equal forces are acting on both sides? Can someone please explain to me . Thanks

Homework Statement I need to explain why I can't lift myself by pulling my shoes' laces. Homework Equations Newton's third law The Attempt at a Solution My explanation is that by pulling on your laces, there is always going to be a force that goes against your force, so this is why you...

Homework Statement Newton's third law of motion is often summarised as 'Every action (force) has an equal and opposite reaction'. A book rests on a table. If the weight of the book is the 'action' force, what is the 'reaction' force? A the pull of the book on the Earth B the pull of...

Homework Statement A small mass (1 kg) sits next to a larger mass (3 kg) on a table. A force of 5 Newtons pushes from left to right on the system while a force of 3 Newtons pushes from right to left on the system. Am I justified to conclude that the net force on the larger block has magnitude...

Homework Statement Using the equation T = kr^p I drew a loglog graph of orbital time period against orbit radius for the planets Mars to saturn. lnT = plnr + lnk My value for gradient was 5.25/0.48 = 10.94 Meaning p = 10.94 How do I compare this to the actual value? What is it?Homework...

Homework Statement Determine Kepler's third-law constant Ku for Uranus using the data for the first four moons. Homework Equations [/B] (r)^3/(T)^2 = K Data: Moon #1 (Ophelia) r=5.38 x 10^4 km T=0.375 Earth Days The Attempt at a Solution [/B] I know the question asks for the K constant...

we know weight of an object produces a force on the surface of anything on which it is .. but why the surface gives an equal amount of force back to it as friction .. the reason is the third law of motion which states every force produces an equal and opposite amount of force .. so the net...

Homework Statement Homework Equations principle of moments Newton's 3rd law The Attempt at a Solution Okay. I am not asking how to solve this question. I just have a little misunderstanding of the concept of the Newton's Third Law. I will get straight to the point. For example, in this...

when a stone is dropped in a beaker containing water,it sinks.But according to Newton's third law of motion the water should also exert an equal force upwards...so the stone should float. This violating the third law but why?

Hello, I am returning to college after a ten year hiatus and am taking an online course on edx to try and refresh my knowledge a bit before the fall. I read a few other posts on Newton's Third law, but it seems I am falling short on this one concept. In the case of an object, m_1, which is at...

Newton's Third Law concerns the forces of interaction between two bodies. Which of the following statements relating to the third law is not correct ? A. The two forces must be of same type B. The two forces must act on different bodies. C. The two forces are always opposite in direction D. The...

How did Newton predict his third law? If we take the system as the whole universe Newton's third law leads that the net force of the system is zero.Did Newton have an insight about this?

Do weight and normal contact force always act in equal and opposite directions?

Homework Statement Three boxes, A, B, C, are positioned next to each other on a friction-less surface, an applied force acting on box A causes all the boxes to accelerate at 1.5 m/s/s. Calculate the force exerted by box C on box B. ma= 8 kg mb=10 kg mc= 5 kg Homework Equations Fnet=MA The...

Homework Statement If there were a planet three times farther from the sun than the Earth is, how long would it have taken this hypothetical planet to orbit the Sun? Assume the orbit is a circle. Homework Equations Kepler's 3rd Law ##= (\frac{r_1}{r_2})^3 = (\frac{T_1}{T_2})^2 ## The Attempt...

Three High energy Photons spontaneously convert into electron positron pairs, The electron on the left marked A is created and and destroyed within a short interval, sending an electric field burst towards electron B shortly after it's created, just enough so that Electrons B's electric field...

I am the kind of guy that always needs to return to the horse-and-carriage problem to hone in my understanding of Newton's Third Law. Here's my question. Assume a rocket in space is applying a force to another object of equal mass in space. Now, I understand the object in space is experiencing...

If you fill a balloon with air and let it go, since the initial momentum was 0 and the air in the balloon is pushed in one direction, the balloon must move in the other direction. What is the cause of the force that causes the balloon to move this way?

Homework Statement The fictional planet Snazbort has a fictional moon Pingdol. Pingdol has an orbital period of 7.68 days and a semimajor axis of 92.53×109. Use Kepler's Third Law to estimate the mass of Snazbort. Homework Equations T^2=4pi^2*a^3/(GM) where 2a is the length of major axis T is...

Homework Statement Consider Newton’s force law for two particles interact through a central force F12(r1',r2',u1,u2), where by Newton’s third law F12 = -F21. m1(d^2r1/dt^2) = F12(r1,r2,u1,u2) m2(d^2r2/dt^2) = F21(r1,r2,u1,u2) A. Show that Newtonian mechanics is form invariant with respect to...

Please forgive me for my naiveté but I've got to resolve a conceptual problem I'm having. If every action has an equal and opposite reaction then why don't all the forces in the universe cancel each other out. For example if i am in space and I hit a ball with force X then the ball reacts back...

I need some help understanding how Newton's third law applies to field forces (namely gravitation). The third law in contact forces seems straightforward to me. Billiard ball A, which is moving, hits billiard ball B. The collision exerts a force on Ball B, resulting in its acceleration...

Got it!

Homework Statement . question is as attached. answer is 2f/5..how do u get this? Homework Equations F=ma F= (5m)a a= F/(5m) The Attempt at a Solution gotten a=F/5m , but why the answer is 2f/5?

When a horse pulls tonga, the Tonga exerts an equal force on Tonga then why does it move. How is Newton's third law applied to such case.

Homework Statement [/B]Find the normal force exerted on a 68.2 kg blacksmith's anvil by the level block of wood that is supporting it.Homework Equations [/B]f=ma Ff=uFnThe Attempt at a Solution [/B]I have tried to find all the forces acting on the anvil while using its mass but I am not...

Hi, I am facing some issues while dwelling upon the application of Newton's third law of motion to the famous "Horse-Cart" Problem.Anybody who is clueless about what I am talking about please follow the link: https://www.lhup.edu/~dsimanek/physics/horsecart.htm As one can see the whole...

Is the force of attraction between an electron and a proton in a hydrogen atom a example of action and reaction to which Newton's 3rd law applies?

I was confused by a NASA pdf document about flight physics. I provide quote from NASA document instructor's flight manual, flight testing Newton's laws. Document is categorized DFRC-X41-1. Did NASA use some fast-and-loose language right there? Imprecise definition of drag using Newton third...

According to Newton's third law, every force has an equal and opposite reaction force. Which force is equal and opposite to both friction and tension?

1. If Big Bang really happened, then what are the action and reaction forces acting? 2. A quantity like Entropy is always increasing. If average temperature is made constant then universe is getting heated continuously..then what is that being cooled? 3. Total of action and reaction force =0, if...

1. no matter how strong a car engine is a car cannot accelerate on an icy surface 2. A vehicle pushes a car of lesser mass from rest, causing the car to accelerate on rough dirt.

Hello! I'm a high school teacher in physics. I will teach Newtons third law this coming week and found the following question (regarding a horse pulling a carriage): "If the force on the carriage is equal and opposite to the force on the horse how can the horse pull the carriage? Is the...

Hi, I am a little confused with the concept of action reaction pair of forces. Does this depend on mass? For example, if a train engine is pulling a buggy with force F, what would be the force applied by the buggy on the engine? The masses of the two are different and there is force of...

Newton's third law states that for every action, there is an equal and opposite reaction. This doesn't make sense to me, because it seems as though everything would cancel out and so nothing would ever happen. For example, imagine a person attempting to push a large box; not just a quick push...

Why forces acts on two different bodies with same magnitude and opposite in direction doesn't cancel each other?

After being through with Newton's 3rd law of action reaction pairs, there arise a doubt regarding the categorization of force couple (related to torque) of being or NOT being an example of action reaction pairs.

So I've recently read Newton's third law violates the principles of relativity. I only know how to prove conservation of momentum if Newton's third law holds. I was hoping someone could explain to me this (proving conservation of momentum when Newton's third law is false) without using extremely...