问题 填空题

如图1所示是小徐同学做“探究做功与速度变化的关系”的实验装置.他将光电门固定在直轨道上的O点,用同一重物通过细线拉同一小车,每次小车都从不同位置由静止释放,各位

置A、B、C、D、E、F、G(图中只标出了O、G)离O点的距离d分别为8cm、16cm、24cm、32cm、40cm、48cm,56cm.

(1)该实验是否需要测量重物的重力______(填“需要”或“不需要”);

(2)该实验是否必须平衡摩擦力?______(填“是”或“否”);

(3)为了探究做功与速度变化的规律,依次得到的实验数据记录如表所示.请选取其中最合适的两行数据在答题卷的方格纸内描点作图.

(4)从图2的图象得到的直接结论是______,从而间接得到做功与物体速度变化的规律是______.

实验次数1234567
d/×10-2m8.0016.0024.0032.0040.0048.0056.00
v/(m/s)0.490.690.850.991.091.211.50
v2/(m/s)20.240.480.720.981.191.462.25
v
/(m/s)
3
2
0.700.830.921.001.041.101.23

答案

(1)该实验中,根据W=Fs,F=ma和s=

v2t
-
v20
2a
,可得,Fs=
1
2
m
v2t
-
1
2
m
v20
,即外力做功与物体的质量无关,实验不需要测量物体的质量(重力);

(2)该实验中已经测量了物体的位移与速度,来探究合外力与物体的速度的变化关系,所以是否存在摩擦力对该实验没有影响.故不需要平衡摩擦力.

(3)根据表格中记录的数据可得,物体的位移d与物体的速度、以及速度的平方根都不存在正比例的关系,与速度的平方接近正比例关系,所以可选择v2为坐标系的纵坐标.将表格中的数据在d-v2坐标系中描点连线如图.

(4)从图2的图象得到的直接结论是d与v2成正比;从而间接得到做功与物体速度变化的规律是合外力做功与v2成正比.

故答案为:(1)不需要;(2)否;(3)如图;(4)d与v2成正比,合外力做功与v2成正比.

单项选择题
阅读理解

The booking notes of the play “the Age of Innocence”:

Price: $10

BOOKING : There are four easy ways to book seats for performance:

★in person

The Box Office is open Monday to Saturday, 10 a. m. -8 p. m.

★by telephone

Ring 01324976 to reserve your tickets or to pay by credit card(Visa, MasterCard and Amex accepted)

★by post

Simply complete the booking form and return it to Global Theatre Box Office.

★on line

Complete the on-line booking form at www. Satanfied theatre.com

DISCOUNTS:

Saver: $2 off any seat booked any time in advance for performances from Monday to Thursday. Savers are available for children up to 16 years old, and full-time students.

Supersaver: half-price seats are available for people with disabilities and one companion. It is advisable to book in advance. There is a maximum of eight wheelchair spaces available and one wheelchair space will be held until an hour before the show.

Standby: best available seats are on sale for $6 from one hour before the performance for people eligible(suitable)for Saver and Supersaver discounts and thirty minutes before for all other customers.

Group Bookings: there is a ten per cent discount for parties of twelve or more.

School: school parties of ten or more can book $6 standby tickets in advance and will get every tenth ticket free.

Please note: we are unable to exchange tickets or refund money unless a performance is cancelled due to unforeseen circumstances.

小题1:If you want to book a ticket, you CANNOT _____

A.go to the Box Office on Sundays.

B.ring the booking number and pay for the tickets by credit card.

C.use the Internet.

D.complete a booking form and post it to the Box Office.小题2:According to the notes, who can get $2 off?

A.The people who book the tickets on Fridays.

B.An 18-year-old teenager.

C.A 55-year-old woman.

D.A 20-year-old full-time college student.小题3:If you make a group booking for a group of 14 adults, how much should you pay?

A.$120

B.$126

C.$140

D.$150