Class Starter - AP Physics Quiz – Buoyancy 1.Please clear off your desks of everything except your data sheets, a piece of paper, a calculator and a pencil 2.Set up a divider between yourself and your neighbour 3.When you are finished hand it in at the front of the room!
Challenge! - Float your Boat 1.Please form your groups for the challenge 2.Send someone to the front of the room to let me know what option you have chosen 3.Collect a yellow basin from the front and fill it with at least 2 inches of water 4.DO NOT start just yet
Hmmmm…. Consider the following Using a whiteboat and pens from the front discuss the following questions with your group…. 1.What changed occurred that lead your boats to go from floating to then sinking…? 2.Why were some boats able to carry more mass than than others? 3.In general, why do do some solid bodies float on a fluid while others do not? Boat Write-up due next class! (Use Goggle Docs to create!)
Hydrostatics Challenge Question Stay in your groups to answer the following questions! 1.Next Class: Fluid Flow (we are HALF way through module 1) 2.Watch Video (notes) #3 – Fluid Flow + MC Questions 1,3,6,9,10,11,15,19,20,23,26,29-32,35,39,41,46 3.Collect some whiteboards, let’s go over some AP Q’s!
MC Q’s 1.In a large tank of liquid, the hydrostatic pressure at a given depth is a function of: a. depth b. surface area c. liquid density d. object density e. a and c f. a and d 2.Dams at two different locations are needed to form a lake. When the lake is filled, the water level will be at the top of both dams. The Dam #2 is twice as high and twice as wide as Dam #1. How much greater is the force of the water on Dam #2 than the force on Dam #1? (Ignore atmospheric pressure; it is pushing on both sides of the dams.) a. 2 b. 4 c. 8 d. 16 e. 32
MC Q’s ANSWERS 1.In a large tank of liquid, the hydrostatic pressure at a given depth is a function of: a. depth b. surface area c. liquid density d. object density e. a and c f. a and d 2.Dams at two different locations are needed to form a lake. When the lake is filled, the water level will be at the top of both dams. The Dam #2 is twice as high and twice as wide as Dam #1. How much greater is the force of the water on Dam #2 than the force on Dam #1? (Ignore atmospheric pressure; it is pushing on both sides of the dams.) a. 2 b. 4 c. 8 d. 16 e. 32
MC Q’s 3.A large stone is resting on the bottom of the swimming pool. The normal force of the bottom of the pool on the stone is equal to the: a.weight of the stone. b. weight of the water displaced. c.sum of the weight of the stone and the weight of the displaced water. d.difference between the weight of the stone and the weight of the displaced water. e.weight of the water in the swimming pool. 4.A heavily loaded boat is floating in a pond. The boat starts to sink because of a leak but quick action plugging the leak stops the boat from going under although it is now deeper in the water. What happens to the surface level of the pond? a. It stays the same. b. It goes up. c. It goes down. d. More information is needed
MC Q’s ANSWERS 3.A large stone is resting on the bottom of the swimming pool. The normal force of the bottom of the pool on the stone is equal to the: a.weight of the stone. b. weight of the water displaced. c.sum of the weight of the stone and the weight of the displaced water. d.difference between the weight of the stone and the weight of the displaced water. e.weight of the water in the swimming pool. 4.A heavily loaded boat is floating in a pond. The boat starts to sink because of a leak but quick action plugging the leak stops the boat from going under although it is now deeper in the water. What happens to the surface level of the pond? a. It stays the same. b. It goes up. c. It goes down. d. More information is needed
Q5 a.Calculate the absolute pressure at an ocean depth of 1000 m. Assume that the density of water is 1000 kg/m 3 and that P o = 1.01 x 10 5 Pa (N/m 2 ). b.Calculate the total force exerted on the outside of a 30.0 cm diameter circular submarine window at this depth.
Q5 Answer a.Calculate the absolute pressure at an ocean depth of 1000 m. Assume that the density of water is 1000 kg/m 3 and that P o = 1.01 x 10 5 Pa (N/m 2 ). b.Calculate the total force exerted on the outside of a 30.0 cm diameter circular submarine window at this depth. 9.9x10 6 N/m x 10 6 N
Q6 A bargain hunter purchases a "gold" crown at a flea market. After she gets home, she hangs it from a scale and finds its weight in air to be 7.84 N. She then weighs the crown while it is immersed in water (density of water is 1000 kg/m 3 ) and now the scale reads 6.86 N. Is the crown made of pure gold if the density of gold is 19.3 x 10 3 kg/m 3 ? (Density of gold = 19,300 kg/m 3 )
Q6 Answer A bargain hunter purchases a "gold" crown at a flea market. After she gets home, she hangs it from a scale and finds its weight in air to be 7.84 N. She then weighs the crown while it is immersed in water (density of water is 1000 kg/m 3 ) and now the scale reads 6.86 N. Is the crown made of pure gold if the density of gold is 19.3 x 10 3 kg/m 3 ? (Density of gold = 19,300 kg/m 3 ) 0.98 N m kg 8000 kg/m 3
Q7 It was determined that a 400N input force could lift a 4000N weight on the other side (i.e. that with the greater area). If the amount of input force does not increase, how can it lift a greater weight? If anything, the fact that the force is spread over a larger area on the output side suggests the overall pressure exerted on that side would decrease. Where does that extra force come from?
Q7 Answer If the amount of input force does not increase, how can it lift a greater weight? Pressure is a measure of Force/Area, if the area increases the Force increases Where does that extra force come from? In order to lift the second lever even a short distance, the first lever must be cover a large distance (see diagram to the right) W in = W out