Sometimes balance point may not be obtained on the potentiometer wire why​

Write a full page that sumerizes thermodynamics it’s from the website visionlearnig

Consider a small frictionless puck perched at the top of a fixed sphere of radius r. if the puck is given a tiny nudge so that it begins to slide down, through what vertical height will it descend before it leaves the surface of the sphere? [hint: use conservation of energy to find the puck's speed as a func e conservation of energy to find the puck's speed as a function of its height at what value of this normal force does the puck leave the sphere? ] here on the puck.

The voltmeter reads 117 v and ammeter reads 0.13 a .if the resistance of ammeter and voltmeter are 9 kilo ohm and 0.015 ohm respectively ,find the value of r. 3marks