A 7.6 −kg box having an initial speed of 4.5 m/s slides along a rough table and comes to rest.

Question

A 7.6 −kg−kg box having an initial speed of 4.5 m/sm/s slides along a rough table and comes to rest. Estimate the total change in entropy of the universe. Assume all objects are at room temperature (293 KK).

Express your answer to two significant figures and include the appropriate units.

Answer 1

Let

m = 7.6 kg be the mass of the box,

v = 4.5 m/s be initial velocity,

T = 293°K be ambient temperature.

The initial kinetic energy of mv²/2 gets converted to heat.

That is

ΔQ = mv²/2

Then use the definition of entropy

ΔS = ΔQ/T

to calculate the change in entropy.