问题 填空题

小明用弹簧拉力器锻炼身体时发现:用力拉弹簧时,开始不会感到太费力,可越到后面越费力,这是什么原因?你的解释是______.

答案

弹簧被拉长时,会发生形变,而发生弹性形变的物体要恢复原状就会对接触它的物体产生力的作用,即弹力;

且弹簧被拉的越长,弹力就越大,拉起来就越费力.

故答案为:弹簧受到的拉力越大,弹力越大.

阅读理解

Surrounded by the towns of Davidson, Huntersville and Cornelius, Lake Norman is a man-made lake. It is also the largest lake in the state covering a shoreline of more than 500 miles. State Park on the lake gives a chance for different water activities.

People, both tourists and locals, come to the area on weekends, where during the peak season a large crowd arrives to relax and have fun. A great activity for kids is education except fun. The tour covers aquatic(水生的) life, especially that seen at Lake Norman. Since it is more of an educational one it also covers other important knowledge about water.

Those wanting to go boating are seen off into the lake on canoes and pedal boats which are rented on hourly basis. The charges are $5 per hour increased by $3 for every additional(附加的) hour. The boats can be kept on the lake all day from 10 in the morning till 5 in the evening during the summers. Both canoes and pedal boats can seat 2 to 4 people.

The park also set up a group tent camp, where a site can hold about 25 people. People from all over the country come here to catch some fishing action, obviously hoping to catch some fish as well. The inner park lake is also great for fishing, though it offers a smaller area compared to Lake Norman. Those here for adventure like to go for biking and hiking on the trails inside the park.

Lake Norman is a great place to spend time with family and friends. People come here on vacation or simply to kick back after a week’s work and relax.

小题1:From the passage we learn that Lake Norman is ______.      

A.the second largest lake in the USA

B.surrounded by the town of Davidson

C.not a natural one but made by people

D.about five hundred metres long小题2:A large number of people came to the park ______. 

A.to watch the performances here

B.during the peak season

C.to have sports games

D.all the year round小题3:In what way does the park attract children except having fun?

A.Learning a lot.

B.Catching fish.

C.Going hiking.

D.Going cycling.小题4:How much will you have to pay at least if the five of you want to go boating a day?

A.28 dollars.

B.36 dollars.

C.23 dollars.

D.46 dollars.小题5:If you want to save more money you can ______.  

A.stay in the hotel that is near the park

B.come to the park in summer or spring

C.stay in the tent of the park for the night

D.fish in the small lake in the park

问答题 简答题