A coffee maker makes coffee by passing steam through a mixture of coffee powder, milk and water. If the steam is mixed at the rate of $50 \,g$ per minute in a mug containing $500 \,g$ of mixture, then it takes about $t_0$ seconds to make coffee at $70^{\circ} C$ when the initial temperature of the mixture is $25^{\circ} C$. The value of $t_0$ is close to .......... $s$ (ratio of latent heat of evaporation to specific heat of water is $540^{\circ} C$ and specific heat of the mixture can be taken to be the same as that of water)
A coffee maker makes coffee by passing steam through a mixture of coffee powder, milk and water. If the steam is mixed at the rate of $50 \,g$ per minute in a mug containing $500 \,g$ of mixture, then it takes about $t_0$ seconds to make coffee at $70^{\circ} C$ when the initial temperature of the mixture is $25^{\circ} C$. The value of $t_0$ is close to .......... $s$ (ratio of latent heat of evaporation to specific heat of water is $540^{\circ} C$ and specific heat of the mixture can be taken to be the same as that of water)
- [KVPY 2018]
- A
$30$
- B
$45$
- C
$60$
- D
$90$
Similar Questions
Explain why :
$(a)$ a body with large reflectivity is a poor emitter
$(b)$ a brass tumbler feels much colder than a wooden tray on a chilly day
$(c)$ an optical pyrometer (for measuring high temperatures) calibrated for an ideal black body radiation gives too low a value for the temperature of a red hot iron piece in the open, but gives a correct value for the temperature when the same piece is in the furnace
$(d)$ the earth without its atmosphere would be inhospitably cold
$(e)$ heating systems based on circulation of steam are more efficient in warming a building than those based on circulation of hot water
Explain why :
$(a)$ a body with large reflectivity is a poor emitter
$(b)$ a brass tumbler feels much colder than a wooden tray on a chilly day
$(c)$ an optical pyrometer (for measuring high temperatures) calibrated for an ideal black body radiation gives too low a value for the temperature of a red hot iron piece in the open, but gives a correct value for the temperature when the same piece is in the furnace
$(d)$ the earth without its atmosphere would be inhospitably cold
$(e)$ heating systems based on circulation of steam are more efficient in warming a building than those based on circulation of hot water
Steam at $100\,^oC$ is passed into $22\,g$ of water at $20\,^oC$ The mass of water that will be present when the water acquires a temperature of $90\,^oC$ (Latent heat of steam is $540\,cal/g$) is ......... $\mathrm{g}$
Steam at $100\,^oC$ is passed into $22\,g$ of water at $20\,^oC$ The mass of water that will be present when the water acquires a temperature of $90\,^oC$ (Latent heat of steam is $540\,cal/g$) is ......... $\mathrm{g}$
Two identical bodies are made of a material for which the heat capacity increases with temperature. One of these is held at a temperature of $100^{\circ} C$, while the other one is kept at $0^{\circ} C$. If the two are brought into contact, then assuming no heat loss to the environment, the final temperature that they will reach is
Two identical bodies are made of a material for which the heat capacity increases with temperature. One of these is held at a temperature of $100^{\circ} C$, while the other one is kept at $0^{\circ} C$. If the two are brought into contact, then assuming no heat loss to the environment, the final temperature that they will reach is
Mercury is of ten used in clinical thermometers. Which one of the following properties of mercury is not a reason for this?
Mercury is of ten used in clinical thermometers. Which one of the following properties of mercury is not a reason for this?
- [KVPY 2016]
Suppose there is a hole in a copper plate. On heating the plate, diameter of hole, would
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