INTERACTIONS OF FORCES
- Magnets can exert a push or a pull
1) Identify the characteristics of magnets
- Can be made of iron or steel.
- Have two poles. A freely suspended magnet comes to rest pointing in a North-South direction.
- Unlike poles attract and like poles repel.
- Magnets attract magnetic materials.
2) How to make a magnet
- Using one end (pole) of a magnet, stroke it on a magnetic object eg iron rod.
- Repeat process for about 15 times using the same end in the same direction.
- Test the newly made magnet on some iron fillings or paperclips. If it attracts the fillings, the iron rod is magnetized and can act as a magnet.
- The end of the rod which last touched the North pole of the magnet, becomes the South pole and vice versa.
- Using a battery, electrical wire and an iron rod.
- Coil the iron rod with the electrical wires for about 5 rounds and connect the ends of the wire to the battery.
- The iron rod is then ready to be used as a magnet.
- This type of magnet is called an electromagnet and loses all its magnetism when there is no current in the wire or it is removed from the coil.
- Magnets made this way can vary its strength by the number of coils around the magnet and the number of batteries used.
3) Effects of a force
- can move a stationary object.
- can speed up, slow down or change the direction of motion.
- can stop a moving object.
- may change the shape of an object.
4) Different types of forces
- magnetic force
- gravitational force
- elastic spring force
- frictional force
5) Effects of fiction on the motion of objects
- Slow down moving object.
- Stop moving object.
6) Effects of forces on springs
- When we pull a spring it is stretched.
- When we push a spring it is compressed.
INTERACTIONS WITHIN THE ENVIRONMENT
7) Identify the factors that affect the survival of an organism
- Physical characteristics of the environment eg. temperature, light and water
- Availability of food
- Type of other organisms present eg. producers, consumers, decomposers
8) Effect on organisms when environment becomes unfavourable
- Adapt and survive
- Move to other places
9) Trace the energy pathway from the Sun through living things
- Producers absorb light energy from the Sun and convert it into chemical energy in the form of glucose using the process photosynthesis.
- Consumers get the energy from the glucose by consuming the producers.
- Decomposers break down dead organisms and releases nutrients into the air as carbon dioxide. Carbon dioxide is taken in by producers for photosynthesis.
10) Differentiate among the terms
- Organism: is a living thing
- Population: a group of plants or animals of the same kind, living and reproducing at a given place and time.
- Community: many populations living together in a particular place.
- serve to enhance survival and can be structural or behavioural.
- cope with physical factors
- obtain food
- escape predators
- reproduce by finding and ttracting mates or dispersing seed/fruits
12) Man's impact
- Positive: conservation, reforestation
- Negative: depleting natural resources, deforestation, pollution (land/water/air), global warming.