The center of mass of an object may not change, but every point around the center of mass may change. This is rotational motion. How to apply Newton's Laws to rotation. This is a simple concept that relates torque to angular acceleration.
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00:00Hi friends, good afternoon everyone. Thank you for being an active viewer on the Diggus Science channel.
00:11In this series, we will learn about Newton's laws of rotation.
00:17Consider the following object. This is a grinding disk.
00:23Initially, this object is not rotating.
00:26After that, this wheel rotates until it reaches a certain angular velocity.
00:32The object that was originally at rest changes to rotating.
00:36What causes this?
00:40Newton discovered that when an object gets torque, the object will experience angular acceleration.
00:47The presence of this angular acceleration causes the angular velocity of the object to change over a certain time interval.
00:56So, in simple terms, if an object experiences a change in angular velocity, a torque must be acting on the object.
01:10Mathematically, this statement can be written as sigma tau equals I alpha,
01:18where I is the moment of inertia of the object about a certain axis.
01:23This quantity can also be called rotational inertia.
01:28We have known this quantity from the first video in this series course.
01:35Alpha is angular acceleration.
01:38You can understand this quantity in more detail after watching the rotational kinematics course.
01:46Of course sigma tau is the resultant torque acting on an object.
01:52Because it is possible for several torques to act on the same object.
02:00From here, we will find three possibilities.
02:03For non-rotating objects, sigma tau is equal to zero.
02:09This value of zero is a fixed value.
02:12This means that this condition also applies to other constant angular velocities.
02:16Objects rotating at constant angular velocity also have sigma tau equal to zero.
02:31The condition when sigma tau is not equal to zero.
02:36In this condition, the object will rotate with constant angular acceleration.
02:46From this visual illustration, when you see an object rotating,
02:49you will be able to guess whether a torque is working on the object or not.
02:58Hopefully this tutorial is useful.
03:01And, don't forget to watch the next video.