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　　化学：The random error is the fluctuating part of the overall error that varies from measurement to measurement. Normally, the random error is defined as the deviation of the total error from itsmeanvalue.

　　Definitions of system error.an instruction that is either not recognized by an operating system or is in violationof the procedural rules. type of: command, instruction, program line, statement. (computer science) a line of code written as part of a computer program

　　物理：A BMX rider is travelling through a dip on a track where the dip is part of a vertical circle of

　　radius 5.0 m. At the bottom of this dip, the rider experiences a reaction force from the

　　ground of 1075 N. Calculate the speed of the rider through this part of the track. The

　　10751

　　combined mass of the rider and bicycle is 75 kg. (Note: ignore the effects of friction)

　　science teacher was twirling a ball on a string as a demonstration of horizontal circular

　　motion. One of the students noticed that the string always dipped at an angle below the

　　horizontal. Let 6 be the angle the string makes with the horizontal. Assume the string has

　　negligible mass.

　　(a)

　　With reference to specific forces, explain why the string always makes an angle