In this case, the passengers will experience a sideways force. If the train goes round a bend at a constant speed, it is undergoing centripetal (or radial) acceleration. Passengers in the train will experience it as a force pushing them back in their seats. If the train is moving in a straight line as it pulls away from the station, it is said to be undergoing linear acceleration. If the train then goes round a bend in the track, it will be accelerating towards a new direction. We'll assume for the moment that once the train reaches its cruising speed and stops accelerating, it will maintain that speed. When a train standing at a platform in a station starts to move and gather speed, it accelerates in the direction of travel. The SI unit of acceleration is metres per second per second or metres per second squared ( m s -2). In mathematical terms, acceleration is the derivative of velocity with respect to time, and the second derivative of position with respect to time.Īcceleration is a vector quantity (it has both magnitude and direction). Note that if the velocity's magnitude is changing, it is accelerating regardless of whether the magnitude is increasing or decreasing (we all speak colloquially about deceleration on occasion, but the term is not generally used by physicists). It could describe a change in either the magnitude of the velocity or the direction of the velocity, or both. This sounds like a contradiction in terms, especially considering that we use the term “geostationary” to describe many of these satellites, but we'll see in due course why it really is the case that these orbiting objects are accelerating.Īcceleration describes the rate of change of velocity with respect to time. The Moon, for example, is accelerating, as are all of the World's orbiting satellites. There are also some not so obvious examples of acceleration, most of which you can see in the night sky, either with the naked eye or with the aid of a telescope. All of these things are examples of things that are accelerating. We may even be fortunate enough to witness the launch of a NASA or ESA space mission. A train leaving a platform, a car pulling away from a set of traffic lights, an aircraft taking off, or an apple falling from a tree. We can see examples of objects that are accelerating all around us. An object that is accelerating due to a gravitational force, but has no other forces acting upon it, is said to be in free fall. The result of the net force acting on the object is called acceleration. In order for the object's speed or direction to change, it must experience a net force in some direction. it moves at a constant speed in a straight line). We have seen that an object in an inertial frame of reference is either at rest or has a constant velocity (i.e.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |