Question

PHYSICS energy principle and momentum principle question help!!

Problem 12 Joule's paddle wheel experiment consists of a falling weight which spins a paddle-wheel in an insulated barrel of water. As the weight falls, the water warms up. Assume idealized conditions with no friction in the pulley, string, and bearings. How much does the temperature of the water change? Assume there is 0.4 kg of water, the weight has m=100 kg and it falls 1 m. The specific heat capacity of water is 4.2 J/g/K. A) 0.19 degrees B) 0.29 degrees C) 1.16 degrees D) 0.58 degrees E) 3.6 degrees

Answer 1

Applying law of conservation of energy,

Thermal energy of water= Potential energy of weight

$m_{water}*c*\Delta T= m_{weight}*g*h$

Rearranging the above equation in $\Delta T$ and plugging the values,

We get $\Delta T= m_{weight}*g*h/m_{water}*c$

$\Delta T= 100*9.8*1/0.4*4.2*10^{3}=0.583 degrees$

The temperature of the water changes by 0.583 degrees