An iron block of the mass 1 kg is suspended on a spring of the spring constant 140 N/m, and merged into a vessel with 8 liters of water. The mass is displaced by 10 cm from its equilibrium position, and released. How much energy in J has been dissipated by the time the mass comes to a rest?
E = J
.7 OK
HELP: All the initial potential energy has been dissipated.
HELP: The potential energy PE for the spring constant k and displacement x is given by the formula
PE = 1/2*k*x2
(b) What is the mass of water in the container in kg ?
m(water) = kg
8 OK
HELP: 1 liter = 0.001 m3
the density of water is 103 kg/m3
HELP: mass = density*volume
(c) Assuming that the water with the block are thermally isolated from their surroundings, by how much will their temperature increase? Express your answer in C. You will need the values of the heat capacity:
cwater = 4186 J/kg*C
ciron = 448 J/kg*C
Delta T = C
HELP: All the energy from part (a) will be converted to heat.
HELP: If we want to increase the temperature of water by Delta T, we have to increase its thermal energy by
Ewater = cwater*mwater*(Delta T)
The same equation holds for iron if the label water is replaced by iron. But Delta T stays the same, because the temperature of the iron and of the water are the same both at the beginning and at the end.
This hint tells you that the energy from part (a) is equal to
Ewater + Eiron.
So, you can substitute for Ewater and Eiron, and get an equation of the form
Epart (a) = something * (Delta T)
1 answer