1)The outer circumderence of a circular racing track is 60m longer thanthe inner circumference. What is the width of the track?
2)Each wheel of a car has a radius of 25cm.If the car travels at a speed of 50kn/h,how many revolutions does each wheel make in 1 minute?
(give the answer correct to the nearest integer)
3)Three circular gold coins have the same thickness and their radii are 2cm,3cm,4cm respectivey. The three gold coins are melted and recast into one new gold coin. If the new gold coin is just as thick as each of the original three gold coins, find the radius of the new gold coin, correct to 2 sig. fig.
4)The hour-hand and the minute-hand of a clock are 6cm and 11cm long respectively.Find the difference between the distances that the tip of the hour-hand the tip of the minute-hand moves in 42 minutes
5)6 indentical circular disc are cut from a regular metal sheet with area 54cm2 and the remains will be wasted.What percentage of the whole metal sheet is wasted?
area&volume(f.2 level)
2011-06-04 6:23 am
回答 (2)
2011-06-04 6:22 pm
2011-06-04 6:57 pm
No offence:
2. 530 r.p.m. (They ask for nearest integer)
3. unit is missing. Radius of new gold coin = 5.4 cm (They ask for 2 sig. fig.)
4. Distance between the two .... = 46.18 cm
5. % of the whole metal sheet wasted
= (11.5885 cm^2 /54 cm^2) x 100% = 21.46%
2. 530 r.p.m. (They ask for nearest integer)
3. unit is missing. Radius of new gold coin = 5.4 cm (They ask for 2 sig. fig.)
4. Distance between the two .... = 46.18 cm
5. % of the whole metal sheet wasted
= (11.5885 cm^2 /54 cm^2) x 100% = 21.46%
收錄日期: 2021-04-29 17:05:49
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20110603000051KK01030