A shadow forms when light is blocked by an opaque or translucent object. Translucent materials, such as tissue paper, allow partial light through, which scatters and creates a faint shadow. Opaque objects, such as a tree, completely block light and form a dark shadow. Transparent objects, such as glass, do not create a shadow because light passes through in a straight line.Continue Reading
A shadow is cast on the side of the object that is furthest from the light source. The proximity of the object creating the shadow to the light source determines the relative size of the shadow. As an object moves further from a light source, the shadow becomes smaller, and as an object moves closer, the shadow becomes larger. The angle of the light source determines the length of the shadow. At sunrise and sunset, the low angle of the sun creates the longest shadows. The shortest shadows are formed at noon when the sun is highest in the sky.
Most shadows are made up of the umbra and the penumbra. All light is blocked by an opaque object in the umbra. In the penumbra only part of the light is blocked and is an area of partial darkness. For a point source, such as a flashlight shining through a pinhole in a sheet of paper, the shadow that forms is entirely umbra with no penumbra.Learn more about Physics
Momentum is a vector quantity as it is the product of mass and velocity of an object. Mass is a scalar quantity but velocity is vector. In physics, the symbol for momentum is P, and its units are kilogram meters per second and gram centimeters per second.Full Answer >
Because velocity is the rate of motion of an object in a specific direction, either an increase or decrease in the object's speed or a change in its direction of travel causes its velocity to change. This change in velocity is defined as an acceleration, which according to Newton's laws of motion occurs because of an unbalanced force acting on the object.Full Answer >
In physics, "displacement" is defined as the change in position of an object, including how far the object travels and in what direction. If an object moves around but returns to its original position, the object will move though a distance but will not have a displacement.Full Answer >
Since a free-falling object only travels in one direction, its speed is equal to its velocity. The velocity of a falling object is equal to the downward acceleration of gravity times the amount of time that it takes for the object to fall back to Earth.Full Answer >