Energy Exam Style Questions Flashcards
When Brian fully stretches the bow, it stores 10 J of energy.
0 1 . 1 Describe the energy transfer that occurs as Brian stretches the bow.
Chemical potential energy [1] to elastic potential energy [1]
Explain why the speed at which the arrow struck the target was lower than the speed at which it left the bow.
Because some of the kinetic energy of the arrow was transferred [1]
to the thermal energy store of the surrounding air [1]
1 MW = W?
1,000,000 W
Required Practical: specific heat capacity
safety precaution
Place steel cylinder on a heatproof mat / ensure that temperature of steel
cylinder does not get too high / allow steel cylinder to cool down before
handling / ensure that circuit has been properly connected before
switching on / after experiment, allow immersion heater to cool to room
temperature before removing.
0 3 . 3 Alan discovers that the actual value of the specific heat capacity of the
steel used is slightly smaller than that which calculated from the results
of his experiment. Describe and explain one change which he could have
made to the experiment to improve the accuracy of this value.
In our calculation for the specific heat capacity of the steel, we assumed that all of the thermal/heat energy supplied by the (immersion) heater was transferred to the steel, but in reality some of this energy would have been dissipated / transferred to the surroundings [1]. Insulate the cylinder to reduce heat loss to the surroundings [1].
0 1 . 2 Write down two factors which affect the rate at which thermal energy is lost through the walls of a house. -thickness walls -thermal conductivity - type of insulation - temp diff
Any TWO of: the thickness of the walls, the material (or thermal conductivity of the material) from which they are made, the amount/type of insulation used, the temperature difference between the inside and outside of the house (accept ‘the temperature outside’), the surface area of the walls.
0 1 . 3 A nearby terraced house is the same size as the above detached house,
and has been built using the same materials. Explain why the amount of
heat lost from the walls of the terraced house is likely to be lower than
that from those of the above detached house.
Any TWO of: the surface area of the walls of the terraced house (which are
exposed to the outside) is lower [1] which means that the overall rate of
heat transfer through the walls of this house will be lower [1] / less heat
will be lost through the ‘internal’ walls between it and the houses on either
side of it [1].
Required Practical (Main focus) RP2
Heat water to given temperature and pour into beaker [1]. Immediately
replace lid, insert thermometer into water and start stopwatch [1].
Measure temperature decrease of water after set time [1]. Repeat for
(four) additional insulators [1].
3 . 2 State two control variables in this experiment. (RP2)
Any TWO of: initial temperature of water (and beaker) [1]; amount (mass)of water used [1]; cooling time [1]; use of lid [1]; surface onto which beaker is placed [1].
Which of the insulators used had the highest thermal conductivity?
THE MATERIAL THAT HAD THE HIGHEST THERMAL CONDUCTIVITY DECREASED THE TEMPERATURE THE MOST
causes of random error in RP2
repeated the experiment to reduce the effect of random error
random errors: misreading of the thermometer,
a slightly different amount of water being used accidentally for a given measurement, a sudden
change in room temperature (caused for example by a window being opened)
3 . 4 Write down one safety precaution which Mikaela should have taken in
carrying out this experiment.
Any ONE of: take care when using/pouring hot water [1]; do not place
beaker close to edge of table [1]; ensure that beaker does not topple over
[1]; allow beaker to cool sufficiently before emptying water [1].
