Page 40 - FINAL DBS10012_HEAT TEMPERATURE 20102022 (2) (1)

3) A piece of lead of mass 2 kg is dropped from the top floor of a building 32.5 m high. If its
initial gravitational potential energy is converted totally into thermal energy, find the

temperature rise of the lead on hitting the ground.
-1 ° -1
-2
(specific heat capacity of lead = 130 J kg C and g = 10 ms )

Solution:

Let the temperature rise of the lead = q °C

Initial potential energy of the lead = mgh
Heat gained by the lead = mcq

Since no energy is lost,

Heat gained = potential energy
mcq = mgh
q = gh

c

= 10 x 32.5
130

= 2.5°C (Temperature rise of the lead is 2.5°C)

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