Physics Lab 1 PDF

Determination the Viscosity of a Liquid by using the Stock’s Method Aim of the Experiment Study the movement of a small ball falling in a viscous medium and then determine the value of the viscosity of the liquid glycerin using Stoke’s Law Mention the tools used in the experience? 1- One end clos...

Determination the Viscosity of a Liquid by using the Stock’s Method Aim of the Experiment Study the movement of a small ball falling in a viscous medium and then determine the value of the viscosity of the liquid glycerin using Stoke’s Law Mention the tools used in the experience? 1- One end closed longitudinal glass tube containing glycerin, 2- metal balls of material one of regular sizes , 3- metric ruler ,4- stopwatch , 5- micrometer or feet. Q/ State the purpose of dropping balls from one position? - Reduce experimental errors and ensure reliable results. Q/What are the factors affecting the viscosity of the liquid? -(Temperature – Molecular Structure -Intermolecular Forces – Pressure – Impurities). Q/Calculate the viscosity of the liquid D (cm) r (cm) r 2 (cm2) t (sec) ν (cm/s) 𝟑𝟎 First ball 0.88 0.44 0.19 0.75 = 𝟒𝟎 𝟎. 𝟕𝟓 𝟑𝟎 Second ball 0.63 0.31 0.09 1.2 = 𝟐𝟓 𝟏. 𝟐 𝟑𝟎 Third ball 0.32 0.16 0.02 2 = 𝟏𝟓 𝟐 d= 30 cm , ρs = 7.8 g/cm3 , ρl = 1.2 g/cm3 ∆𝒓𝟐 𝒔𝒍𝒐𝒑𝒆 = ∆𝝂 𝟎.𝟏𝟗−𝟎.𝟎𝟗 = 𝟒𝟎−𝟐𝟓 𝟎.𝟏 = 𝟏𝟓 = 0.0066 𝟐 𝜼= 𝒈 (𝝆𝒔 − 𝝆𝒍 ) 𝒔𝒍𝒐𝒑𝒆 𝟗 𝟐 𝜼= 𝟗𝟖𝟎 (𝟕. 𝟖 − 𝟏. 𝟐) 𝟎. 𝟎𝟎𝟔𝟔 𝟗 = 9.4 (g/cm.sec)  Boyle's Law Aim of the Experiment Finding the value of atmospheric pressure (P0) using Boyle's device Mention the tools used in the experience? 1. Thermometer 2. Boyle's device: It consists of a glass tube AB, of regular section, with the upper end closed at either end Its second end is connected to a rubber tube, which in turn is connected to another similar glass tube (CD).The first, but it is open from the end. Most of this device is filled with mercury and then fixed vertically and on Shape the letter U - around a metric ruler. Q/ Why is mercury used to achieve Boyle's law and no other liquids are used?  High Density  Non-Compressibility  Doesn't evaporate easily  Visibility: easy to see and measure in a glass tube.  Chemical Stability: Mercury does not react with most materials, including glass ‫ بما في ذلك الزجاج‬،‫ ال يتفاعل الزئبق مع معظم املواد‬:‫االستقرار الكيميائي‬ Q/ Why is the surface of mercury in the tube convex? - due to the cohesive forces between mercury molecules being stronger than the adhesive forces between the mercury and the glass. Q/ The relationship between gas pressure and volume is: ‫ ـ‬Inversely proportional Q/Calculate the value of atmospheric pressure using Boyle's Law. 𝟏 -1 A (cm) X (cm) Y (cm) h (cmHg) L (cm) (cm ) 𝑳 40 6 6 0 34 0.029 40 7 9.5 2.5 33 0.030 40 8 13.5 5.5 32 0.031 40 9 17 8 31 0.032 𝒑𝟎 = |−𝟕𝟔| 𝒑𝟎 = −𝟕𝟔 𝒄𝒎𝑯𝒈  Yonk's modulus of elasticity Aim of the Experiment Finding the Yonk's modulus of elasticity Mention the tools used in the experience? Horizontal ruler, holder, cuff, weights, micrometer Stress: The force acting on a unit area. Compliance: The ability of a material to deform or respond to applied stress. Q/ What does the Young's modulus depend on and does it have the same value for all substances? Young's modulus does not have the same value for all substances. Each material has a unique value of Young's modulus The key factors it depends on:(Material Composition, Temperature, Microstructure, Impurities and Defects) Q/ Calculate the Young coefficient for the material M (gm) ∆L(mm)→cm 10 0.2→0.02 20 0.6→0.06 ← cm ‫ الى‬mm ‫نحول من‬ 30 1→0.1 40 1.5→0.15 50 2→0.2 W=5 cm ∆𝑳 𝒔𝒍𝒐𝒑𝒆 = ∆𝑴 𝟎.𝟐−𝟎.𝟏𝟓 = 𝟓𝟎−𝟒𝟎 𝟎.𝟎𝟓 = 𝟏𝟎 = 0.005 𝒈 𝒀= 𝒔𝒍𝒐𝒑𝒆 × 𝑾 𝟗𝟖𝟎 𝒀= 𝟎. 𝟎𝟎𝟓 × 𝟓 𝒀 = 𝟑𝟗𝟐𝟎𝟎  Surface Tension Aim of the Experiment Calculating the contact angle and adhesion strength for wax of different colors and indicating the effect of the color of the wax on them. Mention the tools used in the experience? Paraffin (wax in different colors), glass slide, microscope Surface tension: - The effect that causes the surface layer of a liquid to behave like an elastic sheet. - The effect that allows insects to walk on water. - The effect that allows small metal objects such as needles, or pieces of tin foil to float on water. Cohesive forces: The forces that bind matter molecules together. Adhesion forces: The forces that affect between liquid molecules and other circle molecules in contact with it. Q/ What do you expect to happen to the surface tension of a liquid when it reaches its boiling point? - Becomes zero. Q/ What do you expect to happen to the surface tension coefficient of a liquid when its temperature is raised? -Decreases Q/ What are the factors on which the surface tension coefficient of a liquid depends? 1- Temperature, 2- Nature of the Liquid, 3- Impurities, 4- Surfactants (like soap). Q/ Why does a liquid wet some substances and not others? - The variation in the strength of the cohesive forces of the liquid molecules and the adhesion forces with the material surrounding the liquid explains to us why a certain liquid may wet some materials while it does not wet others. Q/ Calculate the angle of contact. X1= 5.4 , X2= 6.2 , Y1= 4.8 , Y2= 5.1 𝑿𝟐 −𝑿𝟏 𝟔.𝟐−𝟓.𝟒 𝟎.𝟖 𝑿= = = = 0.4 𝟐 𝟐 𝟐 Y= Y2 -Y1 = 5.1 – 4.8 = 0.3 𝒕𝒂𝒏𝜽 = 𝑿 𝒀 → 𝟎.𝟑 𝒕𝒂𝒏𝜽 = 𝟎.𝟒 → 𝒕𝒂𝒏𝜽 = 0.75 θ = tan-1(0.75) θ = 36.86  Free Fall Aim of the Experiment Finding the ground acceleration (g) in the case of a free fall of the body and finding the velocity of the body. Mention the tools used in the experience? 1 - A metal ball fixed to a magnetic device. 2 - Mechanical shock sensitive switch. 3- An electronic watch. 4 - metric ruler Q/ Calculate the ground acceleration. S (cm) t (sec) t2 (sec) 100 0.43 0.18 90 0.41 0.16 80 0.38 0.14 70 0.35 0.12 60 0.33 0.10 ∆𝐒 𝒔𝒍𝒐𝒑𝒆 = ∆𝐭 𝟐 𝟗𝟎−𝟖𝟎 = 𝟎.𝟏𝟔−𝟎.𝟏𝟒 𝟏𝟎 = 𝟎.𝟎𝟐 = 500 g = 2× slope = 2× 500 = 1000 cm/s2 =10 m/s2