an object move. an object change direction. Forces can make an object slow down or stop. an object accelerate. an object change shape. A force is a push or pull that acts on an object. Forces can differ in strength and direction. You can’t see but you can see their effects. TYPES FRICTION : when two objects rub against each other. It acts in the opposite direction to the direction of movement. It can slow down or stop a moving object. GRAVITY: which attracts all objects to each other. It causes objects to fall to the ground.
Simple machines have very few components. Complex machines are made up of two or more simple machines. We classify machines by the energy source they use: energy from people Some machines need energy from wind or waterto work fuel such as petrol or diesel electricity their function Mechanical have a motor or engine which transform electricity o the chemical energy stored in fuel into kinetic energy, making things move. (cars) Thermal make things hot or cold. (heaters) Information-processing are used to communicate and to make calculations. (computers) mechanical thermal Information-processing
Complex machines A complex machine is made up of casing: is the outer part of machine. It protects from damage and dust. operational parts: are the individual components of the machine: wheels, axles, gears, levers… mechanism: is a group of components which work together to perform a specific function a motor or an engine: produces movement. Engine needs fuel (petrol or diesel) to work. Motor uses a different energy (electricity …) to work. -Combustion engines use chemical energy. -Electrical motors use electricity. - Microchips have the smallest circuits, they are used in many electronic machines.GEARS Gears are wheels with teeth. One gear can’t work on its own. They perform four functions: They change the direction. They change the speed. They change the amount of force needed. They transfer motion from one place to another.
Technology in our daily lives Technology is the use of scientific knowledge for a purpose. We use At school: interactive whiteboards to look for and share information – internet. In the home: to prepare and cook food quickly. to store fresh food in the freezer. to provide water to keep clean. to do many jobs more efficiently. Modern medicine: to look inside our bodies. (x-ray machines and ultrasound) to crack an important code called the human genome: to find out how our body works. to find cures for diseases. Internet is a global network of computers Some changes in technology can harm the environment
Computers We receive image and sound signals from around the world via communication satellites which orbit the Earth. Wireless signals travelled through the air at the speed of light. Computer technology was developed in the 20 th century. Computers are specially important when a task is very large or when accuracy is necessary. The first computers were big and slow. A microchip contains microscopic circuits which allow the computer to process information quickly. A GPS can locate places, objects and even people throughout the world. It needs 3 satellites to work.