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Form 1 Physics heat transfer topical questions and answers
The Melting point of oxygen is given as #-281.3^0C#. Convert this temperature to Kelvin(K).
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1.
In the set up shown in figure 3, water near the top of the boiling tube boils while at the bottom it remains cold Give a reason for the observation.
2.
State two variables that must be controlled in an experiment for comparing the thermal conductivities of different metal rods of the same diameter.
3.
Give a reason why heat transfer by radiation is faster than heat transfer by conduction.
4.
In fig 4 one end of a metal rod is placed in steam and the other end in melting ice. The length of the rod in between is lagged. State two factors that determine the rate at which ice melts.
5.
A wooden bench and a metal bench are both left in the sun for a long time. Explain why the metal bench feels hotter to touch.
6.
Figure 12 shows two identical containers A and B into which a copper rod is fitted. The containers are well lagged. The liquids in the containers were initially at the same temperature. If the heat is applied continuously at the position shown, state with a reason the container through which the loss of heat is likely to be higher.
7.
Figure 1 below shows a cross –section of a vacuum flask. (i) Name the parts labeled (ii) Explain how the heat losses are minimized when hot liquid is poured into the flask. (iii) Boiling water is poured into two identical vacuum flasks A and B. flask A is partially filled while B is completely filled. Both are closed tightly. State with reasons the flask in which the water is likely to have a high
8.
An electric heater is placed at equal distances from two similar metal cans A and B filled with water at room temperature. The outer surface of can A is shiny while that of B is dull black. State with reasons which can will be at a higher temperature after the heater is switched on for some time.
9.
When a Bunsen burner is lit below wire gauze, it is noted that the flame initially burns below the gauze as shown in figure 5(i). After some time, the flame burns below as well as above the gauze as shown in figure 5(ii) Explain the observation.
10.
Two identical aluminium rods are shown in figure 4. One rests on metal block and other on a wooden block. The protruding ends are heated on a Bunsen burner as shown. State with reason which bar the wax likely to melt sooner.
11.
In a vacuum flask the walls enclosing the vacuum are silvered on the inside. State the reason for this.
12.
The Melting point of oxygen is given as #-281.3^0C#. Convert this temperature to Kelvin(K).
13.
Figure 4 shows two identical balloons A and B. The balloons were filled with equal amounts of the same type of gas. The balloons are suspended at a distances x1 and x2 from a metal cube filled with boiling water and placed on an insulating material. State the mode by which heat travels from the cube to the balloons.
14.
Figure 4 shows two identical balloons A and B. The balloons were filled with equal amounts of the same type of gas. The balloons are suspended at a distances #x_1# and #x_2# from a metal cube filled with boiling water and placed on an insulating material. The face of the cube towards A is bright and shiny and the face towards B is dull black. State with reason the adjustments that should be made
15.
Figure 3 shows a hot water bath with metal rods inserted through one of its sides. Some wax is fixed at the end of each rod. What property of metals could be tested using this set up.
16.
Figure 3 shows a hot water bath with metal rods inserted through one of its sides. Some wax is fixed at the end of each rod. Besides the length of the rods that is kept constant, what else should be kept constant when comparing the property for the different metal rods?
17.
Two identical empty metal containers P and Q are placed over identical Bunsen burners and the burners lit. P is dull black while Q is shiny bright. After each container attains a temperature of #100^0C# the burners are turned off. Two identical test tubes containing water are suspended in each container without touching the sides as shown in figure 3. Explain why container Q may become hot faster
18.
Two identical empty metal containers P and Q are placed over identical Bunsen burners and the burners lit. P is dull black while Q is shiny bright. After each container attains a temperature of #100^0C# the burners are turned off. Two identical test tubes containing water are suspended in each container without touching the sides as shown in figure 3. Explain why the water in test tube in
19.
A paper windmill in a horizontal axis was placed above a candle as shown in figure 2. When the candle was lit the paper windmill begun to rotate. Explain this observation.
20.
Figure 4 shows identical beakers P and Q full of water at 900C. Two similar cold wet clothes are wrapped, one around the top of P and the other around the bottom Q. State with a reason the beaker in which the water cools faster.
21.
(a) Figure 11 shows how underground room was ventilated. It had two vents, one at A and the other at B. A fire was lit at point C. Explain what happened to the ventilation when fire was lit. (b) Explain how a vacuum flask minimizes loss of heat through radiation. (b) Explain how a vacuum flask minimizes loss of heat through radiation.
22.
Figure 3 shows a piece of wood fitted into a copper pipe and a piece of paper wrapped tightly around the junction. It is observed that when a flame is applied around a paper at the junction, the side of the paper around the wood burns first. Explain this observation.
23.
Figure 4 shows a source of heat placed at equal distances from two identical flasks X and Y containing air. The surface of X is painted black while Y is clear. X and Y are linked by a U-tube filled with water whose level S and T are initially the same; it is later observed that S falls while T rises. Explain this observation.
24.
Figure 6 shows a glass tube with water fitted with two identical thermometers A and B. it is heated as shown. State with reason which one of the two thermometers shows a higher temperature.
25.
Explain how a greenhouse gets warm.
26.
State two ways in which mercury based thermometer can be modified to read very small temperature changes.
27.
Figure 3 shows two metal rods A and B of equal length made of same material but different diameters. Wax is attached at one end of each rod. A source of heat is placed between the two metal rods. State with reason, what is observed on the wax.
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