lab 10; Apr 16 — buoyancy

Lab #10
Archimedes’ Principle and
Physics 111 Specific Heat Capacity Name:
1. [26 pts total] Bouyant force=amount of fluid pushed aside: Obtain an object with an unknown
volume and mass, V and m. Zero the empty force probe hanging from the lab stand.
Hit the “Collect” button with nothing on the force probe—your reading should be zero.
Next, hang the mass on the force probe using a string—wait for the reading to settle down.
Then, place a flask of water under the mass until the mass is completely submerged, but
not touching the bottom of the flask.
[6 pts] Record your data below.
Reading with nothing on the probe:
Reading with mass on the probe:
Reading with mass submerged:
a. [6 pts] Draw and correctly label the free body diagram for the mass first while it is hanging in
air, then hanging submerged in water.
Mass hanging in air
Calculate the magnitude of all forces.
Mass hanging in water
Calculate the magnitude of all forces.
b. [4 pts] Calculate the
mass of the object:
c. [6 pts] The density of water is 1.00g/cm 3 =1,000kg/m 3 . Using what you know about the
buoyant force acting on the mass, determine the volume V of the object.
d. [4 pts] Calculate the density of the object. (Note: This is where geologists’ method of
determining an object’s “specific gravity” originates; “specific gravity” is simply an object’s
density in g/cm 3 . This is also a method used in sports medicine to determine body density.)
Archimedes’ Principle–1

Lab #10
Archimedes’ Principle and
Physics 111 Specific Heat Capacity Name:
2. [32 pts total] Specific heat capacity ‘c’: Q=mcΔT. In this part of the lab, you will put a heated
unknown material in a water-filled container and measure its heat capacity.
[6 pts] Initial Data (before adding hot unknown)
Mass of empty aluminum container
Mass of container filled ¾ full with water
Initial temperature of water and container
Take your unknown from the hot water and quickly place it in your container.
[6 pts] Final Data (after adding hot unknown)
Temperature of hot unknown in boiling water
Final temperature of water, container and unknown
(after placing unknown in water and T has stabilized)
Mass of unknown (after removal from container)
A. Calculate the following, showing your work clearly.
a. [4 pts] Find the magnitude of the heat energy gained by your water.
b. [4 pts] Find the magnitude of the heat energy gained by the inner aluminum container.
c. [4 pts] Calculate the magnitude of the heat energy lost by the unknown.
d. d[4 pts] Calculate the specific heat of the unknown material.
e. [4 pts] Identify your material from a table of specific heats. And no, appearance (color) alone
isn’t sufficient. Check your numbers with a staff member.
Archimedes’ Principle and Specific Heat Capacity–2