影响滑轮组机械效率的主要因素有______，______、______．另外对同_爱下问搜题

搜题请搜索小程序“爱下问搜题”

问题填空题

影响滑轮组机械效率的主要因素有______，______、______．另外对同一滑轮组，所挂重物越重，机械效率越______．

答案

（1）因为对重物做的功是有用功，所以重物重力大小可能会影响机械效率；

对动滑轮要做额外功，所以动滑轮重力也会影响机械效率；

还有绳子重力以及摩擦都可能影响机械效率．

（2）对同一滑轮组来说，当额外功一定，所挂重物越重，做的有用功越多，有用功占总功的百分比越大，即机械效率越高．

故答案为：动滑轮重力；摩擦及绳重；提升物体的重力；高．

单项选择题 A1/A2型题

下列部件一定安装在X线管头内的是（）

A.mA表

B.接触器

C.限时电阻

D.定子线圈

E.高压交换闸

问答题

Tanah Baru Sdn Bhd is a private limited company whose sole object is the manufacture of office furniture.Recently, the board of directors decided to expand its business to venture into ostrich farming. Pursuant to this decision the company purchased and obtained delivery of 2,000 ostriches from Ostry Sdn Bhd at a cost of RM 1 million. They are contemplating purchasing another 2,000 ostriches in two months’ time.Madeline, a member of Tanah Baru Sdn Bhd, is completely opposed to the idea of ostrich farming as it is outside the scope of the objects of the company.Required:Advise Madeline on the following:

(a) whether the contract of Tanah Baru Bhd to purchase ostriches from Ostry Sdn Bhd can be challenged on the ground that it is outside the objects clause of the company and she could have the transaction set aside; (4 marks)