2. The height of the cylinder is10cm. If its height is reduced by 3 cm, its surface area is reduced by 94.2 cm 2. What is the surface area of the original cylinder in square centimeters?
3. How many square centimeters of iron sheet is needed to make a cylindrical can with a bottom radius of 5 cm and a height of 10 cm?
4. A cylindrical grain depot, measured from the inside, with a bottom circumference of 62.8m and a height of 3m. If each cubic meter of rice weighs 545 kilograms, how many tons of rice can this grain depot hold?
5. Use a piece of iron sheet with a length of 28.26m and a width of 5m to enclose a cylindrical grain depot with the largest volume (excluding the loss at the joint). What is the volume of this grain depot?
6. The bottom radius of the cylindrical bucket is 20cm. After the iron block is taken out of the bucket, the water level in the bucket drops 1cm. What is the volume of this iron block in cubic centimeters?
7. Fill a conical container with a bottom radius of 6 cm and a height of 10 cm with water, and then pour the water into a cylindrical container with a bottom radius of 5 cm. How high is the water level?
There is a pile of conical sand on the construction site. The circumference of the bottom is measured to be 25. 12m, and the height is 3m. Now use a sand truck that can hold 4 cubic meters at a time. How many times can it be shipped?
9. An approximate conical camping tent with a bottom radius of 3 meters and a height of 2 meters. If everyone occupies 2.4 square meters, how many people can live in this tent? (Numbers are reserved as integers. )
10. On the map with the scale of 1: 30000, it is measured that A and B are 4 cm long. Then, on the map with the scale of 1: 20000, how long can two places measure?
11.On September 10, 2009, the torch of the National Games was passed from A to B. On the map with the scale of 1: 8000000, the distance between A and B was 2.5 cm. What is the actual distance between a and b?
12. On the map with the scale of 1: 300000, the distance between A and B is 50 cm. If two buses, A and B, leave from A and B relatively at the same time, and after 10 hour, bus A travels 76 kilometers per hour, then how many kilometers does bus B travel per hour?
13, a cylindrical steel bar, with a section length of 2.5 meters, has a cross-sectional diameter of 6 cm. If the weight of steel per cubic centimeter is 0.0078 kg, how many kg does the cut steel weigh? (Keep the whole kilogram. )
14, the height of cylinder and cone is equal, and their total volume is 60 cubic centimeters. How many cubic centimeters is the volume of a cylinder?
15, another cone-shaped sand pile, with a bottom diameter of 6m and a height of 4m, 1.7 tons per cubic meter of sand. How many tons does this pile of sand weigh? (Numbers are reserved as integers. )
16. 12 The cylindrical ventilation pipe is made of iron sheet. The diameter of the bottom surface of each ventilation pipe is 8 microns and the length is 60 microns. How many square meters of iron sheet do you need at least? (Numbers are reserved as integers. )
17. Cut a cylinder with a height of 10 cm into several equal parts to form an approximate cuboid. If the length of this cuboid is 3 1.4 cm, how many cubic centimeters is the volume of the cylinder?
18. There are two cylinders with the same bottom area, and the ratio of their heights is 7: 5. The volume of the taller cylinder is 175 cubic centimeters, and the volume of the shorter cylinder is how many cubic centimeters?
19. Cut a cuboid block with a square cross section and remove the largest cone. Given that the diameter of the cone bottom is 2cm and the height is 9cm, what is the volume of the cut-off part?
20. In a cubic iron block with a length of 20 cm, dig out a cone with a bottom diameter of 5 cm and a height of 6 cm, and then melt the remaining iron block to cast a cylinder with a bottom radius of 2 cm and a height of 5 cm. How much can it melt at most? (Numbers are reserved as integers. )