A copper brick having a mass of 20 kilograms is dropped from the top of a tower

Question

A copper brick having a mass of 20 kilograms is dropped from the top of a tower whose hight is 360 meters. The brick falls to the ground. Assuming all of its energy goes to heating it, what is its temperature increase just as it reaches the ground? Recall: (1) the brick only has gravitational potential energy (mgh) at the top of the tower before falling, (2) the specific heat capacity of copper is C = 390 J/kg degreeC 28. The kinetic energy of a motorcycle and rider is 60,000 J, If their total mass is 300 kg, what is their speed?

Explanation / Answer

27)   Block total energy = mgh

                                       = 20 * 9.8 * 630

                                       = 123480 J

=> Temperature increase = 123480/(20 * 390)

                                            = 15.83   degree celsius

28)   Here, kinetic energy = 1/2mv2

=>      60000 = 1/2 * 300 * v2

=>       v    =   20 m/sec

=>    speed =    20 m/sec

=>   v =

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