Q12 of 41 Page 47

A brick weighing 4.0 kg is dropped into a 1.0 m deep river from a height of 2.0 m. Assuming that 80% of the gravitational potential energy is finally converted into thermal energy, find this thermal energy in calorie.

given:


mass=4kg


height=3m


Formula used:


Potential energi=mgh


M=mass


g=9.8m/s


h=height


so


potential energy=4×10× 3=120J


energi converted to thermal energy=0.8× 120=96J


thermal energi in calories=96/4.2=22.8 cal


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