Question about Newton's 3rd law

Thread starter nosecs411
Start date Jan 7, 2008
Tags

Law

AI Thread Summary

Newton's third law explains that every action has an equal and opposite reaction, which occurs on different objects. This means that while the forces are equal in magnitude and opposite in direction, they do not cancel each other out because they act on separate bodies. Understanding this distinction is crucial in grasping the law's implications in physics. The confusion often arises from thinking about forces acting on the same object, which is not the case here. Clarifying this concept can enhance comprehension of Newton's laws in practical scenarios.

Jan 7, 2008

nosecs411

haha I am kinda dumb and all and my physics teacher is like chinese and very unclear (grade eight).

Newton's third law states that "For every action, there is an equal and opposite reaction." I understand most of it but have this question, If the reaction and original force are of the same magnitude in opposite directions, how come they do not cancel each other out?

Physics news on Phys.org

Jan 7, 2008

Doc Al

Mentor

Because they act on different bodies.

Thread 'I've come across another fluid pressure problem I don't understand'

Neglect gravity other than that of water; neglect friction. F1=ρgsh=1000*10*1*(1+4)=50000 N; F1=ρgsh=1000*10*0.1*4=4000 N; F3=50000-4000=46000 N?

View full post »

Thread 'Struggling to understand the concept of this question (ice cube in water optics question)'

TL;DR Summary: I came across this question from a Sri Lankan A-level textbook. Question - An ice cube with a length of 10 cm is immersed in water at 0 °C. An observer observes the ice cube from the water, and it seems to be 7.75 cm long. If the refractive index of water is 4/3, find the height of the ice cube immersed in the water. I could not understand how the apparent height of the ice cube in the water depends on the height of the ice cube immersed in the water. Does anyone have an...

View full post »

Thread 'Variable mass system : water sprayed into a moving container'

Starting with the mass considerations #m(t)# is mass of water #M_{c}# mass of container and #M(t)# mass of total system $$M(t) = M_{C} + m(t)$$ $$\Rightarrow \frac{dM(t)}{dt} = \frac{dm(t)}{dt}$$ $$P_i = Mv + u \, dm$$ $$P_f = (M + dm)(v + dv)$$ $$\Delta P = M \, dv + (v - u) \, dm$$ $$F = \frac{dP}{dt} = M \frac{dv}{dt} + (v - u) \frac{dm}{dt}$$ $$F = u \frac{dm}{dt} = \rho A u^2$$ from conservation of momentum , the cannon recoils with the same force which it applies. $$\quad \frac{dm}{dt}...

View full post »