Science - Physics - Force

Today we were looking at the basics of physics i.e. force, gravity, pressure, velocity, distance, time, mass, weight, pivot, moment, balanced & unbalanced forces, friction etc

I worked with my textbook:  KS3 Science  (Terry Hudson) and with  the BBC KS3 Bitesize section on forces.  I also completed the review and test sections of the BBC KS3 Bitesize and got 6/6 and 11/12 respectively.

Some of the things I learnt about are the units these are measured in and the formulas that are used to work out word problems.

Force is measured in Newtons (N).  Force is the push/pull action. Force is invisible but can be measured and you can see the effect that it has on objects.  FORMULA:  Force = mass x acceleration (Force on the earths surface  = mass x acceleration due to gravity or F=mg)

Velocity is measured in m/s.  FORMULA:  Velocity = Distance /Time (v=d/t)  I also learnt how to isolate the other parts of the formula depending on the information given in the word problem.  i.e. distance = velocity x time    and time = distance/velocity.

An example of a word sum for velocity is:  If a bullet travels 1000m in 2 seconds, what is its velocity?  To work this out is simple:  v=d/t therefore v=1000m/2s so velocity = 500m/s.  (Note the final units)

Some websites we looked at are:
http://www.schoolphysics.co.uk/age11-14/
http://www.physicsclassroom.com/
http://www.gcsescience.com/pfm.htm
http://www.middleschoolscience.com/formulas.pdf

Riddle: What am I

If I appear  once in every minute,
twice in every moment
but not even once in a hundred thousand years,
what am I?

Post your answers in the comment box.