What is meant by the statement that the linear expansivity of copper is 0.17/k?
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oh, and uhmm;
steel bars each of length 3m at 29°c are to be used for constructing a rail line. if the linear expansivity of steel is 1.0×10⁻⁵/k. calculate the safety gap that must be kept between successive bars, if the highest temperature expected is 40°c

1) a child holds two dogs on two separate leads. the dogs are pulling in different directions. one is pulling a force of 20n north and one is pulling 15n eastwards. calculate the resultant force on the child. state the direction. (use the parallelogram of forces) 2) a force of 20n acts horizontally on an object. a second force of 5n acts at 60 degrees to the first one. calculate the resultant force. worth 20 points, need answers asap with method you x