Density and Buoyancy (1)

Name Anthony Cervantes Date 09/26/2023 Class PHYSICS 011 Density and Buoyancy Purpose To learn how to predict whether an object will float or sink. Connections to What You Already Know About in Life You have lots of experience with density and buoyancy! From learning how to float when swimming, playing with toys in the bath, watching an oil and vinegar salad dressing separate, or watching a big heavy boat floating in the water. Buoyancy principles are all around you! Vocabulary Buoyant force, density, displacement, volume Background Eureka! According to popular legend, in the 3 rd century B.C. the famous Greek philosopher Archimedes discovered that there was a relationship between the water he displaced when getting in the bathtub and the buoyant force that made him feel lighter in the water. This discovery lead to the principle named after him which states that “an immersed object is buoyed up by a force equal to the weight of the fluid it displaces.” The shape of an object affects how much fluid is displaced, which explains how a solid block of iron would sink, while the same mass of iron when shaped like a boat would float. Why do some objects float and others sink? The answer lies in the density of the objects and the liquid they are placed in which, in turn, depends on the buoyant forces. Density is the mass of a material in one unit of volume. The mathematical formula for density is given below. Density = Mass Volume or d = m V You can tell if an object will sink or float by comparing the weight of the object and the buoyant force. If the buoyant force is larger, the object has more force pushing up than the weight of the object pulling it down, so it will float. Pre-Lab Question 1. What would you observe if olive oil and water were poured together? Why? If olive oil and water poured together then they are immiscible to each other, and olive oil would settle at the top of water because olive oil is less dense than water. Procedure Section 1 1. Start Virtual Physics and select Density and Buoyancy from the list of assignments. The lab will open in the Density laboratory. 2. You will be measuring the density of solid objects and of various liquids to predict whether the solids will float or sink. You will also calculate the buoyant force on the solids in one of the fluids. Find the ice pg. 1 - Density and Buoyancy © Beyond Labz , all rights reserved

Name Anthony Cervantes Date 09/26/2023 Class PHYSICS 011 ball on the lab wall. Pick up the ball and drag it to the spotlight on the balance. Record the mass in the first table below. 3. Use the Up and Down arrows on the control panel to toggle through the options of fluids to use in the lab. Select Virtual Fluid B . This is a unique Virtual Fluid that is used only in this virtual laboratory. Click the Fill button to release the chosen amount of fluid into the 250 mL graduated cylinder on the laboratory bench. Click on the top of the cylinder to see a zoomed in view of the level of the fluid. Record the volume of the Virtual Fluid in the table. 4. Drag the ice ball to the top of the cylinder and drop it in the cylinder of Virtual Fluid. Click the green Drop button to let the ball fall into the fluid. Look at the close up view window to note the new fluid level in the cylinder with both the Virtual Fluid and the ball. Record the volume in the table. Answer Question 1. 5. Record the volume of the ice sample in the table. Click the blue handle at the bottom of the cylinder to empty the contents of the cylinder. 6. Repeat Steps 2-5 for two more samples: aluminum and pine wood. Record your measurements in the table. 7. Use the formula for density to calculate the density of each of the solid samples. Record the answers in the table. 8. Calculate the weight of each of the objects. Remember Weight = mass  force of gravity (g). Use the mass of the objects in kg and use g= 9.8 m/s 2 . Questions Sample Mass of Sample (g) Volume of Virtual Fluid (mL) Volume of Virtual Fluid and Sample (mL) Volume of Sample (mL) Density (g/mL) Weight of solid (N) Buoyant force in olive oil (N) Ice 14.761 226 242 16 .9226 .1447 .1407 Aluminu m 52.801 228 248 20 2.6401 .5174 .1759 Pine Wood 12.182 228 246 18 .0678 .1194 .1583 1. How can you determine the volume of the ice ball from your measurements? It can be determined by taking the value of the volume of ice and subtracting it from the volume of the virtual fluid which would determine the volume. pg. 2 - Density and Buoyancy © Beyond Labz , all rights reserved

Name Anthony Cervantes Date 09/26/2023 Class PHYSICS 011 Questions Sample Mass of Empty Beaker (g) Mass of Beaker and Sample (g) Mass of Sample (g) Volume of Sample (mL) Density (g/mL) Ethanol 87.173 265.745 178.672 226 .7901 Water 87.173 315.724 228.551 228 1.0024 Olive Oil 87.173 289.978 202.805 226 .8974 2. How can you determine the mass of the ethanol in the beaker? It can be determined by taking the value of the mass of the beaker and subtracting the value of mass with the empty beaker which will give us the total mass of ethanol. 3. Does the weight of an object or its density determine whether or not it will float in a fluid? Explain. It indeed does, the more weight or the density of an object compared to fluids, the object will sink the less the weight of the density of an object to a fluid, the object will float. 4. Which of the solids will float in the olive oil? Explain. Looking at the solid’s densities and weights, only pinewood would float in olive oil because its density is less than that of olive oil. The densities of ice and aluminum surpass olive oils density therefore would cause it to sink. 5. Compare the weight of each object and the buoyant forces to predict which objects will float. Buoyancy force is responsible for floating in that object experiencing a buoyancy force greater than its weight would float. From the table after comparing pinewood would float. Aluminum and ice would sink as their weights are greater than the experiences buoyancy force. 6. If all three solids and all three liquids were mixed in the same cylinder at the same time, what would you observe? List what you would see from the top of the cylinder to the bottom. Explain how you determined your placement. After mixing the liquids they would place themselves weight a denser liquid at the bottom and the less dense liquids at the top. Thus, water would take the bottom level by olive oil and then ethanol would float at the topo. Aluminum being denser than the three liquids would sink to the bottom, ice being pg. 4 - Density and Buoyancy © Beyond Labz , all rights reserved

Name Anthony Cervantes Date 09/26/2023 Class PHYSICS 011 denser than ethanol and olive oil would sink but float immediately above water, and pine wood would float at the top as its less dense than oil and all three liquids. pg. 5 - Density and Buoyancy © Beyond Labz , all rights reserved