问题 计算题

如图所示,光滑圆弧AB在坚直平面内,圆弧B处的切线水平。A,B两端的高度差为0.2m, B端高出水平地面0.8m,O点在B点的正下方。将一滑块从A端由静止释放,落在水平面上的C点处,(g=10m/s2)

小题1:求OC的长

小题2:在B端接一长为1.0m的木板MN,滑块从A端释放后正好运动N端停止,求木板与滑块的动摩擦因数。

小题3:若将木板右端截去长为△L的一段,滑块从A端释放后将滑离木版落在水平面上P点处,要使落地点距O点的距离最远,△L应为多少?

答案

小题1:0.8m

小题2:0.2

小题3:0.16m

前两问各4分,第三问5分。

时,有最大值,即

阅读理解

Visit New York City with your kids where there are numerous things to do which will entertain their spirits and feed their minds.

●The Whispering Gallery

Make your way to the Whispering Gallery. Kids can get a lot of fun there. Once inside the gallery, place one person facing the corner at one end of the room and then place another person facing the corner at the opposite end. Ask one of them to whisper a phrase or a quick sentence and the person at the opposite end will be able to hear every word that was said.

E.42nd St. New York, NY 10017

212-771-5322

grandcentralterminal.com

●American Museum of Natural History

The American Museum of Natural History was founded in 1869. In addition to its impressive exhibits, permanent attractions bring the cool feeling to kids. They can enter the Fossil Halls and take in the impressive dinosaur skeletons. And the Milstein Hall of Ocean Life educates kids on the fragility (脆弱) of the ocean.

Central Park West at 79th St. New York, NY 10024

212-769-5606

amnh.org

●The Scholastic Store

Most parents want their children to read, and moreover, to enjoy reading. The Scholastic Store helps to make that wish a reality by publishing well-written stories that appeal to children, such as Clifford the Big Red Dog, the Magic School Bus and Harry Potter, the Scholastic Store will delight your children.

557 Broadway. New York, NY 10012

212-343-6100

scholastic.com

●Ellen’s Stardust Diner

The restaurant is a place where each person in your family can find something to eat. A diverse menu will satisfy every one’s appetite. Arugula salads, grilled cheese burgers and meatloaf are all on this varied menu. The hall of beauty queens, a drive-in theatre can add to the unique dining experience.

1650 Broadway, corner of 51st St. New York, NY 10019

212-956-5151

ellensstardustdiner.com

小题1:In addition to your favorite food in Ellen’s Stardust Diner, you can also ________.

A.make some good friends

B.meet many beautiful queens

C.receive the first-class service

D.enjoy some entertaining programs小题2:Which of the following websites helps kids learn about ancient animals?

A.ellensstardustdiner.com

B.grandcentralterminal.com

C.amnh.org

D.scholastic.com小题3:The author has written this text probably for ________.

A.children

B.parents

C.educators

D.teachers

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