Recent content by sefatod

Thank you all for your answers ! You're right, I was confused. You really helped me with this one, thank you :smile:

Oh dang I forgot the gravitational force applied to the mass. It is ##F_{grav}=9.8m## so ##||\vec{B}||=0.98m + 9.8m ## so ##||\vec{T}||=-||\vec{B}||=-(0.98m+9.8m)=11m N## !

Oh yes you're right... I rethought about it and found that ##\vec{T}=-\vec{B}## with ##\vec{B}## the force applied to the mass ##m## because the point at the end of the cord is motionless (in the elevator referential) so by the Newton's first law, we have that ##\sum \vec{F_{ext}}=0##. The...

Ok so it is ##T=mg+ma=9.8m-m0.98=m(9.8-0.98)=8.82m N## which is the correction ! Thank you !

TL;DR Summary: Solutions to an exercise coming from the famous "Exercises for the Feynman lectures on physics". I'm stuck on an exercise. "A mass ##m## (kg) hangs on a cord suspended from an elevator which is descending with an acceleration of ##0.1g##. What is the tension T in the cord in...