PHYSICS - LAWS OF MOTION

We will study some physics today. Horray! You need to know some basic physics for the test. We will consider some of the laws of motion and their applications.

NEWTOW'S LAWS OF MOTION

1. A body at rest will remain at rest or if it is in motion, it will continue to move unless an opposing force acts on it. This law explains why if you leave a book on a table, it will be there forever unless somebody moves it. It also explains why somebody is thrown out of a moving car or bus live a projectile when the vehicle comes to a sudden stop. You move at the same speed of the vehicle you continue to move with this speed until the windshield stops you (opposing force)

2. The force on an object is directly proportional to its acceleration and the mass. The acceleration is inversely proportional to the mass. In others words, as the acceleration and the mass increase, the force increases. As the mass increases, the acceleration decreases and vice versa.

Force = Mass x Acceleration 

3. Action and reaction forces are equal but in opposite directions. What does this mean? If you push a wall, you exert an act force on it. The wall pushes you back with the same force (reaction force) which is in the opposite direction. The same thing happens with you standing on the ground.

QUANTITIES

There are two types of quantities used in science.

1. Scalar quantity: This quantity has only magnitude. Example: mass, time, density, volume, distance, speed, etc. Only the magnitude or size matters! For example, traveling 2 miles is distance or traveling at the speed of 2 mph or 2 km/hr.

2. Vector quantity: This quantity has both magnitude and direction. For example, displacement, velocity, weight, force, etc. The direction has to be specified.  For example, traveling 2 miles north is displacement or traveling at the velocity of 2 mph or 2 km/hr west.