# An object tied to an inextensible string is being pe rotated in a vertical circle at a constant speed as “ NN shown: Physics Assignment, NTU

Questions
1. An object tied to an inextensible string is being pe rotated in a vertical circle at a constant speed as “ NN shown. fi ‘ Which one of the following graphs (A. B. C. D or E) best represents the relation between the ’ ot / . . . ‘ ‘ tension J in the string and the angle 0 measured ren from the lower vertical line?

2. A small mass 1 and a big mass Af are connected to the ends of an inextensible string. The string is threaded through a smooth glass tube as shown in the following figure.

The tube is then held by a student and is whirled so that the mass rotates with a constant radius r as shown in the figure at a frequency of 175 revolutions perminute. Given that # = 0.30 kg and M= 0.90 kg.
(1) Calculate the resultant force acting on the mass m. (5 marks)
(11) Calculate the radius r of the circle. (5 marks)
(111) Explain whether it 1s possible for the small mass 7 to be whirled in such a way that the string attached to it becomes horizontal. (5 marks)