Answer:
1. 2.5 mm
2. 0.25 cm
Explanation:
Since the length of the 10 turns of the wire around the pencil is 25 mm, then;
1. the thickness of the wire =
=
= 2.5 mm
The thickness of the wire is 2.5 mm.
2. Since 10 mm = 1 cm, then;
25 mm = 2.5 cm
So that,
the thickness of the wire in centimetre =
=
= 0.25 cm
The thickness of the wire is 0.25 cm.
Answer:
the final temperature = 74.33°C
Explanation:
Using the expression Q = mcΔT for the heat transfer and the change in temperature .
Here ;
Q = heat transfer
m = mass of substance
c = specific heat
ΔT = the change in temperature
The heat Q required to change the phase of a sample mass m is:
Q = m
where;
is the latent heat of vaporization.
From the question ;
Let M represent the mass of the coffee that remains after evaporation is:
ΔT =
where;
m = 2.50 g
M = (240 - 2.50) g = 237.5 g
= 539 kcal/kg
c = 1.00kcal/kg. °C
ΔT =
ΔT = 5.67°C
The final temperature of the coffee is:
ΔT
where ;
= initial temperature = 80 °C
= (80 - 5.67)°C
= 74.33°C
Thus; the final temperature = 74.33°C