Advertisements
Advertisements
प्रश्न
A 50 kg man is running at a speed of 18 km h−1. If all the kinetic energy of the man can be used to increase the temperature of water from 20°C to 30°C, how much water can be heated with this energy?
Advertisements
उत्तर
Given:-
Mass of the man, m = 50 kg
Speed of the man, v = 18 km/h = `18xx5/18=5"m/s"`
Kinetic energy of the man is given by
`K=1/2mV^2`
`K=(1/2)50xx5^2`
`K=25xx25=625 J`
Specific heat of the water, s = 4200 J/Kg-K
Let the mass of the water heated be M.
The amount of heat required to raise the temperature of water from 20°C to 30°C is given by
Q = msΔT = M × 4200 × (30 − 20)
Q = 42000 M
According to the question,
Q = K
42000 M = 625
`rArrM=625/42xx10^-3`
`=14.88xx10^-3`
=15 kg
APPEARS IN
संबंधित प्रश्न
Give reason of Water pipes burst in severe winter.
Give reason of Ice floats on water.
Give reason for Sea water does not freeze at 0°C.
Explain the following:
How can you relate the formation of water droplets on the outer surface of a bottle taken out of refrigerator with formation of dew?
Explain the following:
In cold regions in winter, the rocks crack due to anomalous expansion of water.
A calorimeter contains 50 g of water at 50°C. The temperature falls to 45°C in 10 minutes. When the calorimeter contains 100 g of water at 50°C, it takes 18 minutes for the temperature to become 45°C. Find the water equivalent of the calorimeter.
What do you mean by the anomalous expansion of water?
Describe an experiment to show that water has maximum density at 4°C. What important consequences follow this peculiar property of water? Discuss the importance of this phenomenon in nature.
Draw a graph between volume and temperature, when 5 cm3 of ice at -10°C is heated to form water at +10°C.
What are hot spots? How can you extract energy from a hot spot, if it does not come in contact with underground water?
In cold countries, the water pipes are covered with poor conductors. Why?
The following figure shows a metal cylinder, containing boiling water. One half side A is polished and another half, B is painted black. Two thin metal sheets X and Y are painted black and have one rubber stopper fixed with wax on each sheet. These sheets are equidistant from the boiling water (container A, B) as shown in the diagram. What would you expect to happen after a few minutes? Give a reason for your answer.
Give reasons for the following:
Even when the water in the lakes is frozen, fish can survive.
Observe the given graph and answer the following questions:
- Name the process represented in the figure.
- At what temperature does this process take place?
Write scientific reason.
Placing a plastic bottle filled with water in the freezing compartment in the freezer can cause the bottle to explode.
