Question

A piece of copper of mass 100 g is being drilled through with a 1/2" electric drill. The drill operates at 40.0 W and takes 30.0 s to bore through the copper.
If all the energy from the drill heats the copper, find the copper's increase in temperature. ccopper = 387 J/kg⋅°C.

a. 40.6 C°b. 34.7 C°c. 31.0 C°d. 27.3 C°

Answer 1

Answer:

correct option is c. 31.0°C  

Explanation:

given data

copper of mass = 100 g

electric drill = 1/2"

power = 40.0 W

time = 30 s

C copper = 387 J/kgC

to find out

copper's increase in temperature

solution

we get here energy that is express a s

energy = 40 W × 30 s

energy = 1200 Watt seconds

and heat acquired by drill is here as

heat acquired = 100 × T × 387  

here temperature rise in copper mass as

temperature rise in copper mass = $\frac{100}{1000}$ × T × 387

temperature rise in copper mass = 38.7 ×  T Watt second

we know that all the energy from the drill heats the copper

so we can say

38.7 ×  T = 1200

T = 31°C  

so correct option is c. 31.0°C