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

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

Step-by-step 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} = (1)/(2)mv^(2) \\= (1)/(2) * 2.7 * 4^(2) = 21.6 J \\`

85% of energy is converted into internal energy.

`mc\DeltaT = 21.6 * 0.85 \\2.7 * 385 * \Delta T = 21.6 * 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.