We cannot see forces.We can measure them and sometimes feel the effects they have on things. Forces are measured in newtons (N) Some Types of Force GravityWeight
The force of gravity also exists on the Moon but it is not as strong as it is on the Earth.This is because the Moon is much smaller than the Earth.
Gravity is a force that pulls objectsdownwards towards the centre of theearth
Mass : the amount of matter it containsIt is measured in grams (g) or kilograms (kg) but it is NOT a force.Weight : the force caused by gravity pulling down on the mass of an object. It is measured in newtons (N).
No Objects Mass Weight (g) (N)1 I 100 12 II 200 23 III 300 34 IV 400 4
Upthrust is the force that pushes an object up and makes it seem to lose weight in a fluid. (Remember, a fluid means a liquid or a gas)
When a force work on an object, there always another force that work on it from the opposite site.e.g:
Mass is the amount of matter it containsWeight is the size of the force of the gravitydepends on the object’s mass and its distancefrom the object it’s attracting.
We measure force in newtons. We use aninstrument called a spring balance known asa force meter or a newton meter.
I. Aim: Find out the different of force in the air and in the waterII. Tools and materials Forcemeter Objects that sink in water (glass, plasticin, metal) water Jar
I predict that the weight of the object in theair will be _(higher than, lower than orequal to) _ the weight of the object inwater. If I put more water into the beaker, Ipredict that the reading on the Newtonmeter will __(increase, decrease, or not beany different to before)
Attach an object to the forcemeterCheck the force needed to lift it in the airPut the object on the water in the jar andmake sure that its not touch the bottom ofthe jarRecord your data in a tableRepeat your measurement for 3 timesDo the same thing to other objects
1. Plasticine Weight in Weight in the Upthrust onNo. the air water object (N) (N) (N) I 4 0.5 4 – 0.5 = 3.5 N II 4 1.5 4 – 1.5 = 2.5 NIII 4 1 4–1=3N Average 3N
2. Metal Weight in Weight in the Upthrust onNo. the air water object (N) (N) (N) I 2 1.5 2 – 1.5 = 0.5 N II 2 1.7 2 – 1.7 = 0.3 NIII 2 1.7 2 – 1.7 = 0.3 N Average 0.37 N
Is there any different when you measurethe weight in the air and in thewater?_____Tell the difference___________What type of force that occurs in thisexperiment?