Unit 3 - Forces and Energy
1)​ A marble has a mass of 5 grams and a volume of 2 cm
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Work out the density of the marble, in g/cm3
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2)​ A block of wood has a density of 0.75 g/cm and a volume of 120 cm
Work out the mass of the block of wood, in grams.
3)​ Pictured below is a metal sheet.
The density of the metal sheet is 5.5 g/cm3
Work out the mass of the metal sheet, in grams.
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4)​ Pictured below are two solids – Solid A and Solid B.
Solid A has a density of 1.7 g/cm
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Solid B has a density of 2,750 kg/m
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Which solid has the largest mass – Solid A or Solid B?
5)​ Liquid A has a density of 1.08 g/cm3
Liquid B has a density of x g/cm3
750 cm3 of Liquid A is mixed with 990 cm3 of Liquid B to form Liquid C.
The mass of Liquid C is 1.7 kilograms.
Find the density of Liquid B, to 2 decimal places.
6)​ a. Label the Sankey Diagram Below with input, useful, and wasted energy:​
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b. What is the purpose of a Sankey diagram?
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c. How can you use a Sankey diagram to identify inefficiencies in energy
transfers?
d. Which one of the following could this Sankey diagram represent?
a)​ Hair straightener
b)​ Television
c)​ Kettle
d)​ Printer
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e. Calculate the efficiency of the apparatus shown in 6a.
7)​ A light bulb has an input energy of 200 J and produces 40 J of useful light
energy. Calculate its efficiency.
8)​ A car engine has an efficiency of 25%. If the input energy is 800 J, how much
of it is useful energy?
9)​ In each of the following situations, identify the method of heat transfer taking
place (conduction, convection, radiation). More than one process may be
occurring.
Hot coffee is stirred with a spoon, the spoon gets hot due to _______________.
A chair is placed several feet from a fire in a fireplace. The fireplace has a
glass screen. The side of the chair facing the fireplace gets warm because of
_______________.
A certain type of decorative lamp contains colored liquids. These liquids form
globs that break off and rise to the top of the liquid. The globs rise due to
_______________.
Near the ceiling of a room the air is warmer. The warm air rises because of
_______________.
A college student holds the back of his hand near an iron to see if it is hot.
Heat is transferred to his hand by _______________.
A heater is placed under one corner of a water bed mattress. Warm water
moves throughout the mattress because of _______________.
10)​Complete the sentences:​
a) Energy cannot be _______________ or _______________; it can only be
transferred or transformed.
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b) When energy changes from one form to another, the total energy in a closed
system _______________.
11)​Real-Life Applications:​
a) Describe an example of conservation of energy in everyday life.
b) How does insulation in houses help conserve energy?