Department of Pre-University Education, KarnatakaPUC Karnataka Science Class 11

# 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? - Physics

Sum

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?

#### Solution

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

Concept: Anomalous Expansion of Water
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#### APPEARS IN

HC Verma Class 11, Class 12 Concepts of Physics Vol. 2
Chapter 3 Calorimetry
Q 11 | Page 47