Question

1. A 2.7-kg copper block is given an initial speed of 4.0 m/s on a rough horizontal surface. Because of friction, the block finally comes to rest. (a) If the block absorbs 85% of its initial kinetic energy as internal energy, calculate its increase in temperature.

Answer 1

ΔT = 0.017 °C

Step-by-step explanation:

According to the given condition, the change in internal energy of the block must be equal to 85% of its kinetic energy:

Change in Internal Energy = (0.85)(Kinetic Energy)

`mC\Delta T = (0.85)(1)/(2)mv^2\\\\C\Delta T = (0.425)v^2\\\\\Delta T = (0.425v^2)/(C)`

where,

ΔT = increase in temperature = ?

v = speed of block = 4 m/s

C = specific heat capacity of copper = 389 J/kg.°C

Therefore,

`\Delta T = ((0.425)(4\ m/s)^2)/(389)\\\\`

ΔT = 0.017 °C