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Forces
There are many forces around, including magnetic attraction, gravitational attraction and friction. Certain changes happen when forces act on an object. Forces have direction and can be measured.
Some Useful Words To Remember
Weight - It’s the force of gravity acting on an object. The bigger the gravity the heavier an object becomes. Weight is measures in NEWTONS
Gravity - For us the Earth causes gravity. The moon has gravity too but a lot less. Do you think you would weigh more or less on the moon?
Upthrust - Certain substances like Water can cause a force to act upwards. That force MAKES OBJECTS LIGHTER IN WATER THAN OUT OF IT.
Newton - This is the ‘unit’ people use to measure force. It’s a unit in the same way a gram is a unit for instance. FORCE IS MEASURED IN NEWTONS.
Forcemeter - This is a piece of equipment that measures force.
Stationary - Is an object that is not moving.
Gravity
Gravity is a force which tries to pull two objects toward each other. Anything which has mass also has a gravitational pull. The more massive an object is, the stronger its gravitational pull is.
Earth's gravity is what keeps you on the ground and what causes objects to fall. Gravity is what holds the planets in orbit around the sun and what keeps the moon in orbit around Earth.
The closer you are to an object, the stronger its gravitational pull is. Gravity is what gives you weight. It is the force that pulls on all of the mass in your body toward the centre of the Earth.
Weight In Water
Would you say you weigh more in water than you do out of the water? Ask your teacher to get a forcemeter and measure the weight of something in and out of the water. What can you conclude.? Objects weigh less in water because there is an upward force conteracting the gravitational force .
Friction is what happens when for instance you try and play with your wind up toy can on a carpet. It won’t go as far as if you were playing with it on a wooden floor. That is because the friction created when the car interacts with the carpet is much greater.
Friction happens for instances when two objects interact with each other and effect the way they behave in motion. You will do some friction experiments in school.
Note - Click on the flash window above to activate it
Elastic
When you stretch an elastic band you are acting on it with a force. The more force you put on the elastic band, the more it will stretch. Indeed if you stretch it too far it will snap. The more force the bigger the stretch. The less force the smaller the stretch.
Air Resistance
Did you ever ask yourself why a parachute stops a person from falling to their death. When an object flies through the air, the air itself asks on it and resists the force making it move. This is called air resistance. The bigger the object the bigger the resistance.
Try this! Get a sheet of A4 paper and simply drop it . The air resistance slows it down and it will not fall as fast as a stone - thats air resistance.
Some Cool Links
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Have fun!!!
Remember, as a member of the Science Bus Club you can ‘Ask Albert’ a question about any of the topics. So if you’re not already a member join today!!
