Question

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)

Solution

Correct option is

 

Useful power available = 60% 0f P = 0.6 P watts. Therefore, energy consumed in T seconds = 0.6 PT joules. This energy is used up in heating block. If the rise in temperature , then

                      

or                       

SIMILAR QUESTIONS

Q1

A glass flask of volume 500 cm3 is completely filled with a liquid at 0oC. When it is placed in boiling water at 100oC, 75 cm3 of the liquid overflows. If the coefficient of cubical expansion of glass is  oC-1, what is the coefficient of cubical expansion of the liquid?

Q2

A thin metal square plate has length l. When it is heated from 0oC to 100oC, its length increases by 1%. What is the percentage increase in the area of the plate?

Q3

The density of a liquid of coefficient of cubical expansion . When the liquid is heated to a temperature T, the change in density will be

Q4

Two rods of different materials having coefficient of thermal expansion  and Young’s modulii Y1 and Y2 are fixed between two rigid and massive walls. The rods are heated to the same temperature. If there is no bending of the rods, the thermal stresses developed in them are equal provided

Q5

300 g of water at 25oC is added to 100 g of ice at 0oC. The final temperature of the mixture is

Q6

100 g of ice at 0oC is mixed with 100 g of water 80oC. The final temperature of the mixture will be

Q7

Steam at 100oC is passed into 1.1 kg of water contained in a calorimeter of water equivalent 0.02 kg at 15oC till the temperature of the calorimeter rises to 80oC. The mass of steam condensed in kilogram is

Q8

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

Q9

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

Q10

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?