"End of Chapter Summary and Improvement" Quality and Density PPT

"End of Chapter Summary and Improvement" Quality and Density PPT

Part One: Key Breakthroughs

Type 1 Use of balance

1. Regarding the use of the balance, which of the following operations does not comply with the specifications (C)

A. Do not use a balance to measure objects beyond the measurement range

B. Move the adjusted balance to another place for use. It needs to be readjusted.

C. Take the weight directly by hand

D. Use tweezers to gently move the game code

2. Use a balance to weigh 20 g of a certain powdered chemical. The correct operation method is (D)

A. Place chemicals directly in the left pan of the balance and add 20 g of weight to the right pan.

B. Wrap the chemicals in paper and place them in the left pan of the balance, and add 20 g weight to the right pan.

C. Place a piece of paper on each of the left and right pans, add a 20 g weight to the right pan, and add medicine to the left pan until the balance is balanced.

D. Place the same piece of paper on each of the left and right pans. After adjusting the balance, add a 20 g weight to the right pan and add medicine to the left pan until the balance is balanced.

Type 2 Density and Application of Density Formulas

3. (Harbin High School Entrance Examination) A cup contains 200 mL of milk. The mass of the milk is 210 g, so the density of the milk is 1.05 g/cm3; Xiao Cong drank half the cup, and the density of the remaining half cup of milk remained unchanged (choose Fill in "get bigger", "stay the same" or "get smaller").

4. After reading the table below, Li Bo came to some conclusions, the correct one of which is (A)

A. After 90 cm3 of water freezes into ice, its density becomes smaller and its volume increases by 10 cm3

B. A bottle that can hold 500 g of water must be able to hold 500 g of alcohol.

C. If the density is the same, it must be the same material

D. A solid copper block and a solid lead block have equal masses. The volume of the copper block is smaller than the volume of the lead block.

5. In the experiment of measuring the density of a metal ball, the relevant data are as shown in the figure, then the following statement is correct (C)

A. When adjusting the balance of the crossbeam, if the pointer deviates to the right of the center line of the index plate, the balance nut should be adjusted to the right.

B. The mass of the metal ball is 75.4 g

C. The density of the metal ball is 3.95 g/cm3

D. If the volume is measured first and then the mass is measured, the measured value of density will be smaller.

6. The volume of a stone tablet is 5 m3. Take a small piece as a sample of this stone tablet. Its mass is measured to be 138 g. Use a graduated cylinder to fill 100 mL of water. Then completely put the stele sample into the water and raise the water level to 150 mL. beg:

(1) Density of sample;

(2)The quality of the entire stone tablet.

Type 3 Method of measuring liquid density

7. When Xiao Ming measured the density of a certain edible oil, he performed the following experimental operations:

A. Use a balance to measure the total mass m1 of the beaker and remaining cooking oil.

B. Pour the edible oil to be measured into the beaker, and use a balance to measure the total mass m2 of the beaker and edible oil.

C. Pour part of the cooking oil in the beaker into the measuring cylinder and measure the volume V of this part of the cooking oil.

The correct order of the above operations is BCA (fill in the letters).

End-of-Chapter Summary and Improvement PPT, Part 2: Experimental Activities

Experiment 1: Measuring the density of salt water

1. Experimental principle: ρ=m/V.

2. Experimental equipment: balance, measuring cylinder, salt water, beaker.

3. Experimental steps

(1) Use an adjusted balance to measure the total mass of the salt water and the beaker, record it as m1.

(2) Pour an appropriate amount of salt water into the graduated cylinder and record the volume V.

(3) Use a balance to measure the mass of the remaining brine and the beaker, record it as m2.

4. Calculation formula of salt water density: ρ=(m_1 "-" m_2)/V.

[For training]

1. During the busy farming season, Xiaoqiang prepares salt water based on the physics knowledge he has learned and helps his mother select crop seeds. To screen out good quality seeds, the density of salt water should be slightly less than the density of plump seeds. In order to know whether the density of the prepared brine is appropriate, Xiaoqiang measured it through the following experiments.

(1) Adjust the balance of the balance: Place the balance on a horizontal platform, and move the cursor to the zero mark on the left end of the scale. If you find that the balance beam is higher on the left and lower on the right, you should turn the balance nut to the left (optional "left" or "left"). "right" ) adjustment;

(2) Use an adjusted balance to measure the mass m1 of the empty beaker;

(3) As shown in Figure A, pour an appropriate amount of salt water into the graduated cylinder and measure the volume V of the salt water;

(4) As shown in Figure B, pour the salt water in the measuring cylinder into the beaker, and measure the total mass m2 of the beaker and salt water;

Please complete the form below to record measurement data:

(5) According to the above method, the density value of salt water measured by Xiao Ming may be less than (optional "greater than" or "less than") the true value of the density of salt water. The reason is that after the salt water is poured into the beaker, some of the salt water will remain on the wall of the measuring cylinder. above, causing the measured value of brine quality to be too small.

Experiment 2: Measuring the density of small stones

1. Experimental principle: ρ=m/V.

2. Experimental equipment: balance, measuring cylinder, water, small stones, thin wire.

3. Experimental steps

(1) Use an adjusted balance to measure the mass of the small stone, record it as m.

(2) Pour an appropriate amount of water into the graduated cylinder and record the volume V1.

(3) Tie the small stone with a thin wire, gently put it into the measuring cylinder, submerge it in water, and record the volume V2.

4. Calculation formula of density of small stones: ρ=m/(V_2 "-" V_1 ).

5. Experimental precautions

(1) When measuring the mass, use tweezers to add weights in order from largest to smallest; during the mass measurement process, the balance nut cannot be adjusted.

(2) Pour appropriate amount of water into the measuring cylinder. "Appropriate amount" has two meanings: one is that the small stones can be completely immersed, and the other is that the water surface cannot exceed the measuring range of the measuring cylinder when the small stones are immersed.

[For training]

2. In the experimental class "Measuring the Density of Small Stones":

(1) After correctly adjusting the balance of the balance, placing objects on the balance tray and adding or subtracting weights, if the pointer remains at the position shown in Figure A, the cursor should be moved (to the right). After the balance is balanced, the weight indication and the position of the wandering code are as shown in Figure B, then the mass of the small stone being measured is 52.4g;

(2) Pour 12 mL of water into the measuring cylinder, and then put the small stones into the measuring cylinder filled with water. The position of the liquid level in the measuring cylinder is as shown in Figure C. Then the volume of the small stones is 20 cm3, and the density is 2.62×103kg/m3;

(3) Xiao Ming’s steps when measuring the density of small stones are as follows:

A. Use a balance to weigh the mass m of the small stone.

B. Immerse the small stone in the water in the measuring cylinder and record the scale V1 when the water surface reaches it.

C. Take out the small stones and record the scale V2 where the water surface reaches.

Trial analysis: The density value of the small stones measured by Xiao Ming is too small compared with the actual density value (choose "too large", "small" or "equal");

(4) During the experiment, Xiaoying accidentally broke the measuring cylinder, but there was no measuring cylinder in the laboratory anymore, so the teacher added an overflow cup and a small beaker for her to measure the volume of small stones. The steps are as follows:

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For more information about the PPT courseware "Quality and Density Chapter End Summary and Improvement", please click the Quality and Density ppt Chapter End Summary and Improvement ppt tag.

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