# Buoyancy Lab Essay

620 Words3 Pages
Buoyancy Lab Report I. Theory: In this experiment, we are trying to prove a theory that buoyancy is a force exerted by a liquid, in this case water, which opposes an object's weight. The theoretical buoyant force is given by FB=ρgV with ρ is density (kg/m3), g is gravitational acceleration (m/s2), and V is volume (m3).To measure the buoyant force, we compare the weight of an object in and out of the water by FB=Wout – Win. The simplifying assumptions are no surface tension, no friction, no air resistance, and gravitational acceleration is constant at 9.8m/s2. II. Procedure: Equipment needed is a large beaker, various weights, a track, two levers, a string, force sensor, scale, a car, a tuna can, a sphere, a block, and cylinders. In the first part of the lab, first we predict the theoretical buoyant force water acts on the sphere, the block, and two cylinders using the above equation FB=ρgV and the volume for various shapes is V(sphere)=4/3πR3, V(cylinder)=πR2h, V(block)=LWH. Second we measure the buoyant force for each of those shapes taking its weights in and out of water by the force sensor and the scale respectively. The difference is the buoyant force FB=Wout – Win. Finally we calculate percent error between the theoretical and experimental value for each shape: % error=(Measured – Theoretical)/Theoretical x 100%. In the next part of the lab, we compare the predicted and the measured capacity of a tuna can boat. The predicted capacity is calculated to be 0.183kg, and then we load the boat until it sinks and subtract 0.001kg to get the measured capacity. Finally, we analyze the errors in both parts of the lab by propagation by substitution and compare the theoretical-experimental values using errors. III. Results: The theoretical buoyant forces for the sphere, the small cylinder, the block, and the big cylinder are 0.297N, 0.131N, 0.369N, and