· 4.10 understand that work done is equal to energy transferred
PFY p.112
1)A. Joules, force, distance
b)Newton, meter, force
d) Energy transferred
2) Wd= f x d
Wd= 5 x 2
Wd=10J
4)Wd= f x d
Wd= 500N x 40m
Wd=20000J = 20kJ
Collins p. 91
Wd= f x d
50000= 4000 x d
D= 50000/4000
D=12.5m
· 4.9 recall and use the relationship between work, force and distance moved in the direction of the force:
work done = force × distance moved
Wd = F × d
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Tell the person next to you...
· Imagine pushing a king sized bed from one side of the classroom to the other
· Would it make you feel tired?
o Yup!
· Would you have to work hard to push it?
o Yup!
· What could you change so you have to do less work pushing?
o Anything that decreases the force needed (reduce friction by putting wheels on it, ice under it, etc)
o Anything that decreases the distance travelled (only push it half way!, etc)
o So the formula for work must contain force and distance
a)Conduction, Conductors, Conductors, insulators
b)Convection,sinks, floats
c)Infra-red, reflected, good, good, poor, poor
d)radiation, conduction, convection
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