Frequently Asked Questions...
Physics momentum rope swing problem?
Tarzan is in the path of a pack of stampeding elephants when Jane swings in to the rescue on a rope vine, hauling him off to safety. The length of the vine is 24 m, and Jane starts her swing with the rope horizontal. If Jane's mass is 48 kg, and Tarzan's mass is 91 kg, to what height above the ground will the pair swing after she rescues him? (Assume the rope is vertical when she grabs him.)
Answer:
Jane's speed at bottom of swing = Vj = √2gh = √2*9.8*24 = 21.7 m/s
Then, conservation of momentum kicks in.
Jane's momentum = Pj = MVj = 48*21.7 = 1041.6
When Jane swings in and grabs Tarzan, their combined momentum is conserved and Pc = 1041.6.
Now you can calculate their combined speed, Vc.
Mc = combined mass = 48 + 91 = 139
Pc = Mc*Vc
Vc = 1041.6/139 = 7.49 m/s
Now you get height from h = v^2/2g = (7.49)^2/2*9.8 = 2.86m
And there lies the problem: an elephant can easily be 3 meters tall. Do they survive?
Hope this helps.
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Rescue Rope
GRIMP Day - Technical rope rescue competition
High Rope Training 'What Is It?
Copyright (c) 2010 Filton Kingswood
Mention high rope work and many people think first of the great Charles Blondin who crossed the Niagara Falls on a tightrope in 1859. He followed this up with several more increasingly bizarre crossings including cooking an omelette whilst half way across. Blondin originally trained as an acrobat and relied on his natural sense of balance to get him through.
Nowadays high rope work has evolved to mean working at height on and around any of the tall structures that form part of our modern world. These include sky scrapers, wind turbines, oil rigs, bridges and communications towers. Trained high rope technicians are called upon worldwide to complete a range of projects. These could be as simple as window cleaning on a tall building or as complex as the maintenance and repair of a communications array. In short, where there is a tall structure, high rise technicians are needed.
High rope work is not just confined to man made structures. It is increasingly used to help solve geotechnical problems. With time comes movement, of cliffs, mountains and man-made steep sided gullies. The action of tides can erode the sides of cliffs until they succumb to nature and fall into the sea. Heat, drought, excessive rainfall and ice all play their part in changing the sub-structure of mountainsides and gullies until rock falls and land slips become inevitable. Whilst authorities sometimes yield to nature, they also have to consider the safety of their populations. This leads to the need for projects to shore up and stabilise potentially hazardous land.
All these projects require highly trained rope access technicians. While a number of technicians will bring skills to their training such as mechanical, electrical or electronic, others will merely bring a head for heights and an enthusiasm for a rewarding career. IRATA training can add to these skills and equip technicians for potentially worldwide careers full of interest (and safety).
The Industrial Rope Access Trade Association (IRATA) is a global body for companies working in the rope access industry. Since its formation in 1987, IRATA has worked to ensure the safety of people working in the rope access industry. It has been so successful in this that the accident rate for IRATA members is much lower than for comparable industries.
It is a common misconception in business management that putting a few individuals together and giving them a common task or goal creates a team. It doesn't. True teamwork means recognising your own and others strengths and weaknesses and using them for the good of the whole organisation. True teamwork means watching out for each other and being there with support almost before it is asked for. True team work means being able to rely on others to do what is expected of them so that you can perform your role with a feeling of security. For high rope technicians teamwork = safety = life. Training in teamwork is an important aspect of all IRATA courses.
The key planks of IRATA rope access training are safety and teamwork. Every IRATA job has to have a minimum team of two. Each worker is tethered by two separate ropes attached to different anchorages. Tools and equipment are either separately tethered or tied to the worker. This insistence on separate tethering and second line tethering forms the basis of IRATA safety.
IRATA training consists of a minimum five day course followed by both written and practical exams. All exams are separately assessed by a third party qualified assessor. Passing the first exam will mean qualification as an IRATA level 1 technician. These workers will be able to undertake a range of tasks under the supervision of an IRATA Level 3 technician and be responsible for their own equipment.
To progress to an IRATA level 2 technician requires working for a minimum of one year and 1,000 hours as a Level 1 technician. There is then a further minimum five day course with both written and practical exams at the end. Technicians can then undertake tasks such as rope access rigging and undertaking rescues, including hauling, under the supervision of a level 3 technician.
Those wishing to become IRATA level 3 technicians have to have worked for a minimum of one year and 1,000 hours at level 2. In addition to completing a further course and exam they also have to be nominated by an IRATA member company or assessor and have obtained appropriate first aid qualifications. Level 3 technicians have a comprehensive knowledge of advanced rescue techniques and are conversant with relevant work techniques and legislation. They are also capable of site supervision for rope access projects.
IRATA training doesn't stop with the basic qualifications. All technicians have to undertake a refresher course every two years and those who don't work for a period of six months also have to attend a refresher course and be re-assessed.
These strict training regulations help to ensure the safety of IRATA members. It also means that IRATA technicians are in demand worldwide. Many of the elements of the IRATA course are appropriate in other industries. For that reason you will often find that firms which offer IRATA training will also be able to provide courses in related subjects. These could range from teamwork awareness to fall arrest, rescue training and tower climbing.
About the Author
Rope Access UK is headed by an IRATA level 3 assessor. Click here now for
IRATA Training
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