A light meter rod has two points each of masses 2kg fixed at its ends ...
Problem:
A light meter rod has two points each of masses 2kg fixed at its ends . If the system rotates about its center of mass with angular speed 0.5 rad/second. Find the rotational kinetic energy ?
Solution:
In order to find the rotational kinetic energy of the system, we would need to use the formula:
Kr = (1/2)Iω²
Step 1: Find the moment of inertia of the system
The moment of inertia of the system can be found using the formula:
I = (1/12) ML²
- M = total mass of the system = 4kg
- L = length of the rod = distance between the two points = 2m
Plugging these values into the formula, we get:
I = (1/12) (4kg) (2m)² = 0.67kgm²
Step 2: Find the angular speed of the system
- ω = angular speed of the system = 0.5 rad/second
Step 3: Calculate the rotational kinetic energy of the system
Plugging the values of I and ω into the formula for rotational kinetic energy, we get:
Kr = (1/2)Iω² = (1/2) (0.67kgm²) (0.5 rad/second)² = 0.084J
Step 4: Interpretation of Results
The rotational kinetic energy of the system is 0.084J. This means that the system has this much energy due to its rotational motion.