题目

传送带的速度始终是4m/s，A、B两轮轮心相距6m，现将m=1Kg的小物体轻放到A轮的正上方的皮带上，物体与皮带之间摩擦系数μ=0.2，物块从A轮的正上方运动到B轮的正上方的过程中，求（1）、摩擦力对物块做的功。（2）、物块和传送带转化的热能。（3）、电动机消耗电能是多少？ 答案：【答案】（1）8J；（2）8J；（3）16J 【考点】动能定理的应用；功能关系． 【解析】解：（1）对物块，由牛顿第二定律得： μmg=ma， 代入数据解得：a=2m/s2， 物块速度与传送带速度相等时，物块的位移为： 则物块在传送带上先做匀加速运动，后做匀速运动，则摩擦力对物块做功为： W=μmgx=0.2×1×10×4=8JTODAY, Friday, November 12 JAZZ with the Mike Thomas Jazz Band at The Derby Arms, Upper Richmond Road West, Sheen. w.w.w.zxxk.c.o.m DISCO Satin Sounds Disco. Free at The Lord Napier, Mort lake High Street, from 8a. m. to 8p. m. Tel: 682—1158. SATURDAY, November 13 JAZZ Lysis at The Bull’s Head, Barnes. Admission 60p. MUSICAL HALL at The Star and Garter, Lower Richmond Road, Putney, provided by the Aba Daba Music Hall company. Good food and entertainment fair price. Tel: 789—6749. FAMILY night out? Join the sing-along at The Black Horse, Sheen Road, Richmond. JAZZ The John Bennett Big Band at The Bull’s Head, Barnes. Admission 80p. THE DERBY ARMS, Upper Richmond Road West, give you Joe on the electric accordion(手风琴). Tel: 789—4536 SUNDAY, November 14 DISCO Satin Sounds Disco, free at The Lord Napier, Mort Lake High Street, from 8 a. m. to 8 p. m. FOLK MUSIC at The Derby Arms. The Short Stuff and residents the Norman Chop Trio. Non-members 70p. Tel: 688—4626. HEAVY MUSIC with Tony Simon at The Bull, Upper Richmond Road West, East Sheen. THE DERBY ARMS, Upper Richmond Road West, give you Joe on the electric accordion. 1.. Where and when can you hear the Norman Chop Trio? A. At the Bull’s Head on Sunday. B. At the Derby Arms on Sunday. C. At the Bull on Saturday. D. At the Black Horse on Saturday. 2.. Where and when can you hear the Mike Thomas Jazz Band? A. At the Derby Arms on Friday.            B. At the Black Horse on Friday. C. At the Star and Garter on Saturday.         D. At the Derby Arms on Sunday. 3..You want to enjoy the electric accordion on Saturday. Which telephone number do you have to ring to find out what time it starts? A. 789—6749.          B. 789—4536.       C. 682—1158.       D. 688—4626. 4.. You want to spend the Saturday by joining the entertainment with your family. Where should you go? A. Disco at The Lord Napier.               B. The sing-along at The Black Horse. C. The electric accordion at The Derby Arms.   D. Jazz at The Bull’s Head. 5.. You want to spend the same day at two different places and don’t want to cross any street. Which of the following is your best choice?  l’s Head. B. The sing-along at The Black Horse and Folk Music at The Derby Arms. C. Folk Music at The Derby Arms and Heavy Music with Tony Simon at The Bull. D. Musical Hal lat The Star＆Garter and Disco at The Lord Napier.