PHYS0030 Basic Physics
Questions:
Purpose
To use the principle of balanced torques to find the value of an unknown distance and to investigate the concept of center of gravity.
Theory
First condition of equilibrium
An object doesn’t move. Therefore, the vector sum of all forces exerted on the object must be equal to zero.
(1) Second condition of equilibrium The resting object also doesn’t rotate. Therefore, the sum of all torques exerted on it is zero.
(2) An object balances when all torques on it add up to zero. In this sum, the torques tending to rotate the object in the chosen positive direction should be taken with the sign “plus” whereas the torques tending to rotate the object in the negative (opposite) direction should be taken with the sign “minus”.
Earth’s gravity pulls on every part of an object. It pulls stronger on the more massive parts and weaker on the less massive parts. The sum of all these pulls is the weight of the object. The weight is exerted on the object at its center of gravity, or c.g. In this experiment, you will balance a uniform stick of mass on a pin with two known values (and ) to check the conditions of equilibrium experimentally.
EXPERIMENT
Note: the center of gravity of a uniform stick is at its geometric center (50cm mark)
Set the pivot point at the center of the stick =0 .5 (or 50cm) and choose the stick mass Place = 200 kg mass at = 0.3 (30cm)
Find the position where will produce equilibrium (zero net torque)
Determine the distance X between the and the pivot point.
Questions
1. How well did your experiment check the two conditions of equilibrium? Explain
2. What is the impact of each condition of equilibrium on the motion of a rigid body?
