Question

1. A2 .7-kg copper block is given an initial speed of 4.0m/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.( b) What happens to the remaining energy

Answer 1

Answer:

A. Increase in temperature is 0.0176 degree Celsius. b. the remaining energy will be lost.

Explanation:

The mass of copper block = 7kg

Initial speed = 4.0 m/s

Specific heat of copper = 0.385 j/g degree Celcius.

a. The increase in temperature is calculated below:

$\text{Change in kinetic energy} = \frac{1}{2}mv^{2} \\= \frac{1}{2} \times 2.7 \times 4^{2} = 21.6 J$

85% of energy is converted into internal energy.

$mc\DeltaT = 21.6 \times 0.85 \\2.7 \times 385 \times \Delta T = 21.6 \times 0.85 \\\Delta T = 0.0176 degree \ celsius$

b. The remaining  15 per cent of kinetic energy will be lost and it will be changed into other forms.