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  1. R

    Need a little help

    Ok ive been set the following question: A piece of optical fibre is 150m long. Two rays of light travel along the fibre. One goes along the axis and the other is reflected off the boundary at the critical angle of 85 degrees. What is the difference in time taken by the two rays. Speed of...
  2. R

    What would be the best way

    What would be the best way to go about measuring the temperature of a Lightbulb? I've been set a task to measure the temperature of a lightbulb as i increase the electrical power supplied to it and i was just wondering what would be the most practical way to do it. Any help would be greatly...
  3. R

    Need some help

    A boy is travelling down a slope on a sledge. The boy and the sledge have a total mass of 60kg and are travelling at a constant speed. The angle of the slope to the horizontal is 35 degrees. There are 3 forces acting on him, the weight of him and the sledge acting straight down W, the push from...