Viscosity is a factor controlling resistance to flow and the speed that liquids flow is down to this. The lower the viscosity, the runnier the fluid is. Viscosity can be easily measured using the line spread test, how far and fast a fixed quantity of liquid spreads across a flat surface. Another way is by using George Gabriel Stokes’ method of a falling ball, this method includes timing a ball falling at a constant rate (its terminal velocity) through a substance, the longer it takes for the ball to fall a measured distance the more viscous the substance.
I am investigating how temperature affects the viscosity of honey, in order to do this I must use the falling ball viscometer method first conducting a preliminary experiment to find a suitable range of temperatures of honey to time a ball falling through. Archimedes stated: ‘When a body is partially or totally immerse in a fluid, the upthrust is equal to the weight of the fluid it displaces.
‘ When terminal velocity has been reached by the ball bearing the forces acting upon it will be balanced and the ball bearing will fall at a constants velocity.
The magnitudes of these forces are related: Or: This equation can be rearranged by cancelling common factors of ? and r, multiplying by 3 and ten dividing by 2 to give: ? can then be made the subject: [Salters Horners Advanced Physics Activity Sheet 5] As you can see form the equations, the radius of the steel ball bearing is needed in order for the viscosity to be calculated, this can be done by finding the diameter of the ball bearing and then dividing it by two. I used a micrometer screw gauge to measure the diameter of the ball bearing accurately.
[www. design-technology. org] The ball bearing was inserted into the gap between the anvil and the spindle and the thimble was slowly turned. There are 50 evenly spaced markings around the thimble each representing 0. 01mm since the spindle moves 0. 5mm with every rotation of the thimble. The barrel also has evenly spaced markings each representing 1mm. When we measured the ball bearing, the markings on the barrel showed the diameter to be 10mm and the thimble at 0. 00mm.
The diameter of the ball bearing is 10.00mm correct to one hundredth of a millimetre and so the radius, r, is 5mm. Preliminary A ball bearing was dropped into honey of four different temperatures, being cleaned and dried between each, the time taken for the ball to fall 10cm was recorded. Repeat readings were taken of each temperature of honey to try and ensure no anomalies. The ball bearing was attached to the end of a straw to make it easier to time more accurately the exact moment at which the ball bearing had fallen 10cm.
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How temperature affects the viscosity of honey. (2017, Jul 27). Retrieved from https://studymoose.com/how-temperature-affects-the-viscosity-of-honey-essay