# 6. 20 cm3 of styrofoam is floating in a tub of water. The same volume of gold is submerged in the tub. Which of the objects has a greater buoyant

6.

20 cm3 of styrofoam is floating in a tub of water. The same volume of gold is submerged in the tub. Which of the objects has a greater buoyant force acting on it?

a. The styrofoam

b. The gold

c. The buoyant force is the same in each case

d. Neither has a buoyant force

7.

A cubic block floats in water with 75% of its volume under water. Given that water has a density of 1000 kg/m3, find the density of the block.

a. 1250 kg/m3

b. 1000 kg/m3

c. 750 kg/m3

d. 250 kg/m3

8.

A water-proofed balsa-wood crate is 3.0 m in length, 2.0 m wide, and 0.25 m high. A student begins to load the box with bricks as it sits in a swimming pool. What mass of bricks can be loaded before the crate sinks? Assume the wood is massless and does not break.

a. 1500 kg

b. 2000 kg

c. 3000 kg

d. Can’t determine unless the density of the bricks is given.

9.

Oil (density of 2000 kg/m3) is flowing through a horizontal pipe (cross-sectional area = 0.1 m2). A pressure gauge shows a reading of 25250 Pa in the pipe. The oil is flowing through the pipe at a rate of 0.001 m3/s. The oil encounters a narrowing in the pipe, so that the cross-sectional area reduces to 0.05 m2. Determine the reduction in pressure in the narrower section of pipe.

a. The pressure reduces by 0.9 Pa

b. The pressure reduces by 1.7 Pa

c. The pressure reduces by 0.3 Pa

d. The pressure reduces by 2.8 Pa

10.

A student exhales air over the top of a loosely held sheet of paper. What will occur?

a. The edge of the paper drops due to high pressure above it.

b. The edge of the paper rises due to high pressure above it.

c. The edge of the paper drops due to low pressure above it.

d. The edge of the paper rises due to high pressure below it.

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