Lower Secondary Science - Transportation Science - Pressure PDF

Lower Secondary Science - Transportation Science – Pressure MODULE 2: Transportation Science SCIENCE DEPARTMENT  Lower Secondary Science - Transportation Science – Pressure DISCIPLINE TRANSPORTATION SC...

Lower Secondary Science - Transportation Science – Pressure MODULE 2: Transportation Science SCIENCE DEPARTMENT  Lower Secondary Science - Transportation Science – Pressure DISCIPLINE TRANSPORTATION SCIENCE SCIENCE DEPARTMENT TOPIC DIVERSITY / INTERACTIONS / MODELS / SYSTEMS THEME Motion Science of Modes of EU/EQ Describing Causes of Energy Transport Transport Motion Motion Transfers Land UNIT Describing MODELS Motion Air Forces Sea Energy and Causes of Moments Motion Work Space Speed Density & SYSTEMS Pressure Energy Talks / Transfers Learning INTERACTIONS Journeys LESSON Classroom lessons employing Performance Applied Learning and Technologies Tasks SCIENCE DEPARTMENT Lower Secondary Science - Transportation Science – Pressure UNIT 5: Density & Pressure SCIENCE DEPARTMENT Lower Secondary Science - Transportation Science – Pressure Knowledge Density Pressure Pressure difference Pressure Applications SCIENCE DEPARTMENT  Lower Secondary Science - Transportation Science – Pressure Conceptual Skills (a) Make estimations of mass and volume and calculate the density of liquids and solids. (b) Predict whether an object will sink or float by comparing its density with that of its surrounding medium. (c) Define pressure as the force per unit area. (d) Use the Pascal as unit of pressure. (e) Relate pressure to force and area, using appropriate everyday examples (e.g. high heel shoes, cutting edge of a knife) (f) Recall and apply the formula Pressure = Force/Area in different contexts. (e.g. high heel shoes, cutting edge of a knife) (g) State that a difference in pressure will result in a force. (h) Show an appreciation of some daily life phenomena associated with atmospheric pressure (e.g. use of suction cups, drinking from straws) and pressure due to liquid (e.g. submarines have depth limits) SCIENCE DEPARTMENT Lower Secondary Science - Transportation Science – Pressure Practical Skills (a) Make measurements of volume and mass of liquids and solids using appropriate instruments (measuring cylinder, spring balance, electronic balance) and the methods of using it. (b) Determine density of regular or irregular objects. (c) Demonstrate precision and accuracy in making measurements (taking into consideration parallax errors) SCIENCE DEPARTMENT Lower Secondary Science - Transportation Science – Pressure 5.1 Density Density is defined as the mass per unit volume It is calculated by using density = mass / volume. The SI unit of density is the kilogram per cubic metre (kg/m3). To convert a density from g/cm3, normally the most suitable unit for the size of sample we use, to kg/m3, we multiply by 103. For example the density of water is 1.0 g/cm3 or 1.0 × 103 kg/m3. SCIENCE DEPARTMENT Lower Secondary Science - Transportation Science – Pressure 5.1 Density Some common densities of different materials are shown in the table below: Notice that while liquids are usually expressed in terms of g/cm3, gases are expressed in kg/m3. SCIENCE DEPARTMENT Lower Secondary Science - Transportation Science – Pressure 5.2 Measurement of Density If the mass m and volume V of a substance are known, its density can be found from ρ = m/V. There are several methods of measuring density for a (a) Regularly shaped solid, such as a cube (b) Irregularly shaped solid, such as a pebble or glass stopper (c) Liquid SCIENCE DEPARTMENT Lower Secondary Science - Transportation Science – Pressure 5.2 Measurement of Density (a) Regularly shaped solid, such as a cube 1. The mass is found on an electronic balance, M. 2. The volume is found by measuring its dimensions with a ruler and multiplied using a formula: V = Length X Breadth X Height 3. The density is calculated using M/V. SCIENCE DEPARTMENT Lower Secondary Science - Transportation Science – Pressure 5.2 Measurement of Density (b) Irregularly shaped solid, such as a pebble or glass stopper 1. The mass of the solid is found on an electronic balance, M. 2. The volume V is is found using either method 1 or 2 below. 3. The density is calculated using M/V. SCIENCE DEPARTMENT Lower Secondary Science - Transportation Science – Pressure 5.2 Measurement of Density (b) Irregularly shaped solid, such as a pebble or glass stopper SCIENCE DEPARTMENT Lower Secondary Science - Transportation Science – Pressure 5.2 Measurement of Density (c) Liquid 1. The mass of an empty beaker is found on a balance, Mb. 2. A volume of liquid is measured using a measuring cylinder, VL. 3. The liquid is then poured into a beaker. 4. The mass of the beaker with liquid is measured using the balance, MbL. 5. The mass of liquid is obtained by subtraction, MbL - Mb = ML. 6. The density is calculated by ML/ VL. SCIENCE DEPARTMENT Lower Secondary Science - Transportation Science – Pressure Activity 1: Determining identity of materials using density There are 5 objects, A, B, C, D, and E in the Mystery app (set 1) of the simulation at https://phet.colorado.edu/en/simulations/density Using the scale (left) and the volume indicator of the water tank, determine what each of the 5 objects, A, B, C, D, and E is made of. The list of density of materials (Density Table) are provided within the app. SCIENCE DEPARTMENT Lower Secondary Science - Transportation Science – Pressure Activity 1: Determining density of different materials Object A B C D E Mass /kg Volume /L Density kg/L Identity SCIENCE DEPARTMENT Lower Secondary Science - Transportation Science – Pressure Activity 1: Determining identity of materials using density Object A B C D E Mass 19.3 0.40 19.32 5.00 2.80 /kg Volume 5.5 1.0 1.0 5.0 7.0 /L Density 3.5 0.40 19 1.0 0.40 kg/L Identity Diamond Wood Gold Water Wood SCIENCE DEPARTMENT Lower Secondary Science - Transportation Science – Pressure 5.3 Predicting sinking or floating Watch the following video below and explain how can this happen: https://www.youtube.com/watch?v=QsLqCafXLZ4 Material Density (g/cm3) Cork 0.24 Oil 0.91 Plastic block 0.95 Water 1.00 Grape 1.05 Syrup 1.37 SCIENCE DEPARTMENT Lower Secondary Science - Transportation Science – Pressure 5.3 Predicting sinking or floating What is the principle behind building this tower? _______________________________________________ _______________________________________________ _______________________________________________ See if you can challenge yourselves to build a 12-layer density tower: https://www.youtube.com/watch?v=4EMUsPJtCoc SCIENCE DEPARTMENT Lower Secondary Science - Transportation Science – Pressure 5.3 Predicting sinking or floating What is the principle behind this tower? A less dense liquid will rest on top of a denser liquid if they are not stirred. For an object to float in a liquid, the object has to be less dense than the liquid, or else it will sink. See if you can challenge yourselves to build a 12-layer density tower: https://www.youtube.com/watch?v=4EMUsPJtCoc SCIENCE DEPARTMENT Lower Secondary Science - Transportation Science – Pressure 5.3 Predicting sinking or floating See if you can challenge yourselves to build a 12-layer density tower: https://www.youtube.com/watch?v=4EMUsPJtCoc SCIENCE DEPARTMENT Lower Secondary Science - Transportation Science – Pressure 5.4 Pressure Watch the 2018 Alexey Molchanov's World Record Dive to 130m https://www.youtube.com/watch?v=eu2pBp QolKE SCIENCE DEPARTMENT Lower Secondary Science - Transportation Science – Pressure 5.4 Pressure Pressure is defined as the force exerted per unit area. force pressure = area F P = A SCIENCE DEPARTMENT Lower Secondary Science - Transportation Science – Pressure 5.4 Pressure physical quantity ( symbol ) S.I. unit [ symbol ] pressure ( P ) pascal [ Pa ] force ( F ) newton [ N ] area ( A ) square metre [ m2 ] 1 Pa = 1 N/m2 SCIENCE DEPARTMENT Lower Secondary Science - Transportation Science – Pressure Question 1 & 2 SCIENCE DEPARTMENT  Lower Secondary Science - Transportation Science – Pressure Question 1 A dancer has a weight of 480 N. During a performance, she stands on her toes with a contact area of 25 cm2 with the floor. Calculate the pressure exerted by the dancer on the floor (a) in N/cm2 P=F/A P = 480 N / 25 cm2 P = 19.2 N/cm2 SCIENCE DEPARTMENT Lower Secondary Science - Transportation Science – Pressure Question 1 A dancer has a weight of 480 N. During a performance, she stands on her toes with a contact area of 25 cm2 with the floor. Calculate the pressure exerted by the dancer on the floor (b) in Pa P = 19.2 N/cm2 = 19.2 N/0.0001m2 = 192 000 Pa Note: 1 cm2 = 0.0001 m2 SCIENCE DEPARTMENT Lower Secondary Science - Transportation Science – Pressure Question 2 A box has an area of 0.015 m2 in contact with the ground. The pressure exerted by the box on the ground is 450 000 Pa. Calculate the weight of the box. P=F/A=W/A 450 000 Pa = W / 0.015 m2 W = 450 000 x 0.015 W = 6750 N SCIENCE DEPARTMENT Lower Secondary Science - Transportation Science – Pressure Everyday Application: Increasing the Pressure by Reducing the Area Knife The area under the edge of a knife’s blade is extremely small. Beneath it, the pressure is high enough to push easily through the material to be cut. SCIENCE DEPARTMENT Lower Secondary Science - Transportation Science – Pressure Everyday Application: Increasing the Pressure by Reducing the Area Drawing pin Under the tiny area of the point of a drawing pin, the pressure is far too high for the wood to withstand. SCIENCE DEPARTMENT Lower Secondary Science - Transportation Science – Pressure Everyday Application: Reducing the Pressure by Increasing the Area Skis Skis have a large area to reduce the pressure on the snow so that the skier does not sink in too far. SCIENCE DEPARTMENT Lower Secondary Science - Transportation Science – Pressure Everyday Application: Reducing the Pressure by Increasing the Area Caterpillar tracks fitted to vehicles A larger area of contact with the ground (mud or snow) reduces the pressure of vehicle on the ground. The vehicle will not sink in too far into the ground. SCIENCE DEPARTMENT Lower Secondary Science - Transportation Science – Pressure Video: Travelling on Snow Wheels: https://www.youtube.com/watch?v=UCdmtsnBVLs Tracks: https://www.youtube.com/watch?v=wtB0-6hqi78 SCIENCE DEPARTMENT Lower Secondary Science - Transportation Science – Pressure Question 3 & 4 SCIENCE DEPARTMENT  Lower Secondary Science - Transportation Science – Pressure Question 3 A woman has a mass of 60 kg. (g = 10 N/kg) Calculate the pressure, in pascals, under a woman’s feet when she is weaning a pair of (a) flat shoes with a total area of 300 cm2 P=F/A P=mg/A P = ( 60 ×10 ) / (300 x 0.0001) P = 20 000 Pa Note: 1 cm2 = 0.0001 m2 SCIENCE DEPARTMENT Lower Secondary Science - Transportation Science – Pressure Question 3 A woman has a mass of 60 kg. (g = 10 N/kg) Calculate the pressure, in pascals, under a woman’s feet when she is weaning a pair of (b) high heels with a total area of 25 cm2 P=F/A P=mg/A P = ( 60 ×10 ) / (25 x 0.0001) P = 240 000 Pa Note: 1 cm2 = 0.0001 m2 SCIENCE DEPARTMENT Lower Secondary Science - Transportation Science – Pressure Question 4 The diagram shows a rectangular block of mass 30 kg with dimensions 10 cm by 40 cm by 150 cm. (a) Calculate the weight of the block. (g = 10 N/kg) W=mg W = 30 kg x 10 N/kg W = 300 N SCIENCE DEPARTMENT Lower Secondary Science - Transportation Science – Pressure Question 4 (b) State which face (X, Y, or Z) the block must rest to exert the maximum and minimum pressure on the ground. Calculate pressure in pascal max pressure side: Z P=F/A=W/A P = 300 N / (10 X 40 X 0.0001) m2 P = 7 500 Pa Note: 1 cm2 = 0.0001 m2 SCIENCE DEPARTMENT Lower Secondary Science - Transportation Science – Pressure Question 4 (b) State which face (X, Y, or Z) the block must rest to exert the maximum and minimum pressure on the ground. Calculate pressure in pascal minimum pressure side: X P=F/A=W/A P = 300 N / (150X40X0.0001) m2 P = 500 Pa Note: 1 cm2 = 0.0001 m2 SCIENCE DEPARTMENT Lower Secondary Science - Transportation Science – Pressure 5.5 Atmospheric Pressure The Earth is surrounded by a layer of air known as the atmosphere. The weight of the gas particles in the air exerts a pressure known as the atmospheric pressure. Atmospheric pressure due to air acts in all direction. Atmospheric pressure decreases with attitude (height above sea level). At sea level, the pressure exerted by the atmosphere (atmospheric pressure) is about 100 000 Pa. SCIENCE DEPARTMENT Lower Secondary Science - Transportation Science – Pressure 5.5 Atmospheric Pressure At about the top of mount Everest, it contains 90% of the atmosphere. Hence, we can approximate the atmosphere to be about 10 km above sea level. SCIENCE DEPARTMENT Lower Secondary Science - Transportation Science – Pressure 5.6 Pressure difference and its effects Water Rocket Video https://www.youtube.com/watch?v=mTUGKh rt7fM SCIENCE DEPARTMENT Lower Secondary Science - Transportation Science – Pressure 5.6 Pressure difference and its effects When the ____________________________ a low-pressure zone is created. The surroundings now have a higher pressure. A force will be exerted from the higher-pressure zone to the lower-pressure zone _____________________________________. SCIENCE DEPARTMENT Lower Secondary Science - Transportation Science – Pressure 5.6 Pressure difference and its effects When the temperature of a gas is increased, the gas rises, a low-pressure zone is created. The surroundings now have a higher pressure. A force will be exerted from the higher-pressure zone to the lower-pressure zone to move the gas. SCIENCE DEPARTMENT Lower Secondary Science - Transportation Science – Pressure Examples 5 to 10 SCIENCE DEPARTMENT Lower Secondary Science - Transportation Science – Pressure Example 5 Explain, in terms of pressure, how the heated metallic can crushes on itself. https://www.youtube.com/watch?v=xg5NiOwf_Zw SCIENCE DEPARTMENT Lower Secondary Science - Transportation Science – Pressure When the can is heated, most of the air is removed and a low-pressure zone is created. The surroundings now have a higher pressure. A force will be exerted from the higher-pressure zone to the lower-pressure zone to collapse the tin can. SCIENCE DEPARTMENT Lower Secondary Science - Transportation Science – Pressure Example 6 Explain, in terms of pressure, why did the ping pong ball follows where the tap water goes. https://www.youtube. com/watch?v=PTmJ-pK EjCI SCIENCE DEPARTMENT Lower Secondary Science - Transportation Science – Pressure When the fast water flows around the ping-pong ball, a low-pressure zone is created. The surroundings now have a higher pressure. A force will be exerted from the higher-pressure zone to the lower-pressure zone to keep the ping-pong ball under the water jet. SCIENCE DEPARTMENT Lower Secondary Science - Transportation Science – Pressure Example 7 Explain, in terms of pressure, why was the ping pong ball attracted to the running water. https://www.youtube.c om/watch?v=89-V410V hFw SCIENCE DEPARTMENT Lower Secondary Science - Transportation Science – Pressure When the fast water flows on one side the ping-pong ball, a low-pressure zone is created. The surroundings now have a higher pressure. A force will be exerted from the higher-pressure zone to the lower-pressure zone to keep the ping-pong ball under the water jet. SCIENCE DEPARTMENT Lower Secondary Science - Transportation Science – Pressure Example 8 Explain, using the concepts of pressure, how a suction cup holds up the weight at its hook. SCIENCE DEPARTMENT Lower Secondary Science - Transportation Science – Pressure When the air is removed from the suction cup, a low-pressure zone is created. The surroundings now have a higher pressure. A force will be exerted from the higher-pressure zone to the lower-pressure zone to keep the suction cup in place. SCIENCE DEPARTMENT Lower Secondary Science - Transportation Science – Pressure Example 9 Explain, using the concepts of pressure, how a person drinks from a straw. SCIENCE DEPARTMENT Lower Secondary Science - Transportation Science – Pressure When the person exhales, the lungs are empty and a low-pressure zone is created. The surroundings now have a higher pressure. A force will be exerted from the higher-pressure zone to the lower-pressure zone to cause the liquid to rise up the straw. SCIENCE DEPARTMENT Lower Secondary Science - Transportation Science – Pressure Example 10 (Sea breeze) Explain, in terms of pressure, how the sea breeze is formed. (Note that the land gets heated up faster in the day) SCIENCE DEPARTMENT Lower Secondary Science - Transportation Science – Pressure When the land is heated in the day, hot air rises and a low-pressure zone is created. The surroundings now have a higher pressure. A force will be exerted from the higher-pressure zone to the lower-pressure zone to cause a breeze to move from the sea to the land. SCIENCE DEPARTMENT Lower Secondary Science - Transportation Science – Pressure Example 10 (Land breeze) Explain, in terms of pressure, how the land breeze is formed. (Note that the sea releases heat slowly at night.) SCIENCE DEPARTMENT Lower Secondary Science - Transportation Science – Pressure When the sea releases heat at night, hot air rises and a low-pressure zone is created. The surroundings now have a higher pressure. A force will be exerted from the higher-pressure zone to the lower-pressure zone to cause a breeze to move from the land to the sea. SCIENCE DEPARTMENT Lower Secondary Science - Transportation Science – Pressure 5.7 Pressure due to a liquid column SCIENCE DEPARTMENT Lower Secondary Science - Transportation Science – Pressure 5.7 Pressure due to a Liquid Column Pressure acts in all directions. Liquid pushes on every surface in contact with it, no matter which way the surface is facing. SCIENCE DEPARTMENT Lower Secondary Science - Transportation Science – Pressure 5.7 Pressure due to a Liquid Column Pressure increases with depth. The deeper into a liquid, the greater the weight of liquid above and the higher the pressure. Holes at a different depth beneath the water surface Water will spout the furthest for the deepest hole Liquid pressure is greater at lower depth SCIENCE DEPARTMENT Lower Secondary Science - Transportation Science – Pressure 5.7 Pressure due to a Liquid Column Video https://www.youtube.com/watch?v=2tBWfqKA0Tk https://www.youtube.com/watch?v=K5g6P8-GmBg Holes at a different depth beneath the water surface Water will spout the furthest for the deepest hole Liquid pressure is greater at lower depth SCIENCE DEPARTMENT Lower Secondary Science - Transportation Science – Pressure 5.7 Pressure due to a Liquid Column Pressure depends on the density of the liquid. The denser the liquid, the higher the pressure at any particular depth. https://www.facebook.com/scsdnalab/video s/593014071570689/ SCIENCE DEPARTMENT Lower Secondary Science - Transportation Science – Pressure 5.7 Pressure due to a Liquid Column Pressure does not depend on the shape of the container. Whatever the shape or width of a container, the pressure at a particular depth is the same. The pressure at points A, B, C and D are the same. SCIENCE DEPARTMENT Lower Secondary Science - Transportation Science – Pressure 5.7 Pressure due to a Liquid Column Pressure does not depend on the shape of the container. Whatever the shape or width of a container, the pressure at a particular depth is the same. Water shoots out with same speed and same distance. SCIENCE DEPARTMENT Lower Secondary Science - Transportation Science – Pressure Thanks THE END SCIENCE DEPARTMENT