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1. Figure 1 shows a beam balance made out of concrete and reinforced with steel
Use a diagram to explain the behaviour of the shape of the beam when heated up
2. (a) Sate two liquids which are used in thermometer.
(b) With a reason, state which of the two liquids in 3 (a) above is used to measure temperature in
areas where temperatures are:
. (i) below -400c (ii) 1500c
3. What do you understand by the statement ‘lower fixed point’ on a temperature scale?
4. Name two adaptations that can be made to a mercury thermometer to make it more sensitive
5. Figure 5 shows a bimetallic strip made of brass and iron. A marble is placed at end A of the bimetallic strip as shown below:-
fig. 5
State and explain what will be observed when the bimetallic strip is strongly cooled
6. The figure below represents a bimetallic strip of metals X and Y at room temperature
The figure below shows its shape when dipped into crushed ice
Sketch a diagram in the space given below to show the shape when the strip is heated to a
temperature above the room temperature
7. Give a reason why a concrete beam reinforced with steel does not crack when subjected to
Changes in temperature.
Thermal expansion Answers
1.
- The beam expands linearly
– The beam remains straight but longer than before heating
– Both concrete and steel have same rates of expansion
– Their value of linear expansivity is 11×10-6
2. a) – Alcohol. 1 mk
– Mercury. 1 mk
b) i) below -40oc alcohol ½ because it has a low freezing point of –115oc.
Mercury freezes ½ at -39oc.
ii) 150oc
mercury ½ because it has a high boiling point of 357o,
alcohol boils at 78oc. ½
3. – This is the temperature of pure melting ice at standard/normal atmospheric pressure
(Both pure and standard pressure mentioned;
4. – Using a thin walled bulb 1
– Using a narrower capillary tube 1
5. On cooling, the brass contracts more than iron, hence become shorter than iron and forms upwards curve, making the marble to roll and settle at the centre of the curve.
6.
