1. 1) 1/4 2) 1/3 3) 4/3 4) 3/4 5) 2/1 An object floats in water with 3/4 of its volume submerged. What is the ratio of the density of the object to that of water?

2. Remember that we have: volume of the displaced water to the volume of the object is 3/43/4 the density of water so if the ratio of the volume of the displaced water to the volume of the object is 3/4, the object has 3/4 the density of water. 1) 1/4 2) 1/3 3) 4/3 4) 3/4 5) 2/1 An object floats in water with 3/4 of its volume submerged. What is the ratio of the density of the object to that of water?

3. 1) it floats just as before 2) it floats higher in the water 3) it floats lower in the water 4) it sinks to the bottom The object is now placed in oil with a density half that of water. What happens?

4. object has 3/4 the density of water 1/2 the density of waterdensity of the object is larger than the density of the oil We know from before that the object has 3/4 the density of water. If the water is now replaced with oil, which has 1/2 the density of water, the density of the object is larger than the density of the oil. Therefore, it must sink to the bottom. 1) it floats just as before 2) it floats higher in the water 3) it floats lower in the water 4) it sinks to the bottom The object is now placed in oil with a density half that of water. What happens?

5. Two beakers are filled to the brim with water. A wooden block is placed in the beaker 2 so it floats. (Some of the water will overflow the beaker). Both beakers are then weighed. Which scale reads a larger weight? same for both

6. displaces an amount of water equal to its weight weight of the overflowed water is equal to the weight of the blockbeaker in 2 has the same weight as that in 1 The block in 2 displaces an amount of water equal to its weight, since it is floating. That means that the weight of the overflowed water is equal to the weight of the block, and so the beaker in 2 has the same weight as that in 1. Two beakers are filled to the brim with water. A wooden block is placed in the beaker 2 so it floats. (Some of the water will overflow the beaker). Both beakers are then weighed. Which scale reads a larger weight? same for both

7. A block of wood floats in a container of water as shown on the right. On the Moon, how would the same block of wood float in the container of water? Earth Moon

8. weight of water equal to the object’s weight less weightalso has less weight A floating object displaces a weight of water equal to the object’s weight. On the Moon, the wooden block has less weight, but the water itself also has less weight. ConcepTest 15.14bWood in Water II A block of wood floats in a container of water as shown on the right. On the Moon, how would the same block of wood float in the container of water? Earth Moon

9. (1) one quarter (2) one half (3) the same (4) double (5) four times Water flows through a 1-cm diameter pipe connected to a 1/2-cm diameter pipe. Compared to the speed of the water in the 1-cm pipe, the speed in the 1/2-cm pipe is:

10. A  r 2 radius is reduced by1/2area is reduced by 1/4speed must increase by 4 times (A  v) The area of the small pipe is less, so we know that the water will flow faster there. Since A  r 2, when the radius is reduced by 1/2, the area is reduced by 1/4, so the speed must increase by 4 times to keep the flow rate (A  v) constant. ConcepTest 15.15aFluid Flow (1) one quarter (2) one half (3) the same (4) double (5) four times Water flows through a 1-cm diameter pipe connected to a 1/2-cm diameter pipe. Compared to the speed of the water in the 1-cm pipe, the speed in the 1/2-cm pipe is: v1v1 v2v2

11. 1) increases 2) decreases 3) stays the same 4) drops to zero A blood platelet drifts along with the flow of blood through an artery that is partially blocked. As the platelet moves from the wide region into the narrow region, the blood pressure:

12. Thespeed increases in the narrow part speed is higherpressure is lower The speed increases in the narrow part, according to the continuity equation. Since the speed is higher, the pressure is lower, from Bernoulli’s principle. ConcepTest 15.15bBlood Pressure I 1) increases 2) decreases 3) stays the same 4) drops to zero A blood platelet drifts along with the flow of blood through an artery that is partially blocked. As the platelet moves from the wide region into the narrow region, the blood pressure: speed is higher here (so pressure is lower)

13. A person’s blood pressure is generally measured on the arm, at approximately the same level as the heart. How would the results differ if the measurement were made on the person’s leg instead? Assume the cross-sectional areas of veins/arteries are the same throughout the body. 1) blood pressure would be lower 2) blood pressure would not change 3) blood pressure would be higher

14. A person’s blood pressure is generally measured on the arm, at approximately the same level as the heart. How would the results differ if the measurement were made on the person’s leg instead? 1) blood pressure would be lower 2) blood pressure would not change 3) blood pressure would be higher Assuming that the flow speed of the blood does not change, then Bernoulli’s equation indicates that at a lower height, the pressure will be greater. ConcepTest 15.15cBlood Pressure II

15. How is the smoke drawn up a chimney affected when there is a wind blowing outside? 1) smoke rises more rapidly in the chimney 2) smoke is unaffected by the wind blowing 3) smoke rises more slowly in the chimney 4) smoke is forced back down the chimney

16. How is the smoke drawn up a chimney affected when there is a wind blowing outside? 1) smoke rises more rapidly in the chimney 2) smoke is unaffected by the wind blowing 3) smoke rises more slowly in the chimney 4) smoke is forced back down the chimney Due to the speed of the wind at the top of the chimney, there is a relatively lower pressure up there as compared to the bottom. Thus, the smoke is actually drawn up the chimney more rapidly, due to this pressure difference. ConcepTest 15.16The Chimney