Question

A 1.5 kg copper block is given an initial speed of3.00m/s on a

rough horizantal surface. Because of friction, theblock finally
comes to rest.
(a)If the block absorbs 85% of its initial kinetic energy
asinternal energy, calculate its increase in temperature.
(b)what happens on the remaining energy?

Answer 1

a. 0.01 C

b. dissipated to outside environment

Step-by-step explanation:

Let the specific heat of copper be 0.3846 kJ/kg-K or 384.6 J/kg-C

(a)The original kinetic energy of the block is:

`E_k = (mv^2)/(2) = (1.5*3^2)/(2) = (1.5*9)/(2) = 6.75 J`

As 85% of this kinetic energy is converted to block internal heat energy, with specific heat we can calculate the rise in temperature:

`E_h = 0.85E_k = 0.85*6.75 = 5.7375 J`

`mc_c\Delta T = 5.7375`

`1.5*384.6\Delta T = 5.7375`

`\Delta T = (5.7375)/(1.5*384.6) \approx 0.01^oC`

(b) the remaining 15% energy would probably be dissipated to outside environment as heat energy