Lesson 6 of 11 · 10 min
Equilibrium of a particle
NCERT § "Equilibrium of a Particle"
Over the stadium gate hangs a 10 kg team banner, held at one knot by two ropes: one at 30° above the horizontal, the other at 60°. Which rope is working harder?
The lesson in notes
In short
A particle is in equilibrium when the net external force on it is zero; it is then at rest or in uniform motion.
Two forces keep a particle in equilibrium only if they are equal in size and opposite in direction.
Three concurrent forces in equilibrium add to zero and can be drawn head to tail as a closed triangle.
In practice, resolve every force along two perpendicular axes and set the sum of components along each axis to zero.
A mass hanging from two strings is the standard case: the vertical components of the tensions together balance the weight, and the horizontal components cancel.
Simulations in this lesson
Each on its own page
In past papers
NEET and JEE Main