Question

A wire of cross-sectional area A at temperature t is held taut with negligible tension between two rigid supports. If the wire is cooled to a temperature  what tension is developed in the wire? The coefficient of linear expansion is  and the Young’s modulus of the wire is Y.

Solution

Correct option is

 

Let be the length of the wire at temperature  and  be the contraction in the length as the temperature  falls by  Then

                          

  is

                          

 

SIMILAR QUESTIONS

Q1

If there are no heat losses, the heat released by the condensation of xgrams of steam at 100oC into water 100oC converts y grams of ice at 0oC into water at 100oC. The ratio y/is nearly

Q2

One mole of oxygen is heated from 0oC, at constant pressure, till its volume increases by 10%. The specific heat of oxygen, under these conditions is 0.22 cal g – 1 K – 1. The amount of heat required (in joules) is

Q3

A drilling machine of power P watts is used to drill a hole in copper block of mass M kg. If the specific heat of a copper is s J  and 40% of  the power is lost due to heating of the machine, the rise in the temperature of the block in T seconds will be (in oC)

Q4

A geyser, operating on LPG (liquefied petroleum gas) heats water flowing at the rate of 3.0 litres per minute, from 27oC to 77oC. If the heat of combustion of LPG is , how much fuel in grams is consumed per minute?

Q5

A copper block of mass 2 kg is heated to a temperature of 500oC and then placed in a large block of ice at 0oC. What is the maximum amount of ice that can melt? The specific heat of copper is 400 j  and latent heat of fusion of water is .

Q6

The dimensions of the coefficient of thermal conductivity are

Q7

Two different metal rods of the same length have their ends kept at the same temperatures and  with . If A and are their cross-sectional areas and k1 and k2 their thermal conductivities, the rate of flow of heat in the two rods will be the same if

Q8

Two rods A and B of different materials are welded together as shown in Fig. If their thermal conductivities are k1 and k2 , the thermal conductivity of the composite rod will be

                                                        

Q9

A one liter flask contains some mercury. It is found that at different temperatures the volume of air inside the flask remains the same. What is the volume of mercury in the flask? Given the coefficient of linear expansion of glass  oC–1, the coefficient of volume expansion of mercury is  oC–1.

Q10

Two uniform brass rods A and of length l and 2and radii 2r and rrespectively are heated to the same temperature. The ratio of the increase in the length of A to that of B is