Class Management | Help HWE02II Begin Date: 9/6/2018 70000 AM--Due Date: 9/11/20
ID: 1878030 • Letter: C
Question
Class Management | Help HWE02II Begin Date: 9/6/2018 70000 AM--Due Date: 9/11/2018 70000 AM End Date: 12/10/2018 7:0000 AM (25%) Problem 1: A 75 kgrunner takes off after a starter's pistol fires and reaches a speed of 8 m/s in 1.4 seconds. 33% Part (a) Assuming that the net force is constant on the runner, what is the runner's average speed during the interval? cosO cotan as acos0 atan acotan sinh0 cos anh cotanh ODegrees O Radians sin0 NO I give upl Submit | Hints : 0 for a 0% deduction Hints remaining: 0 Feedback: 0% deduction per feedback. 33% Part (b) what was the distance covered in that mterval? (Are we still assum ng the constant net force?) 33% Part (c) Is the constant rate of change of the speed required, is the constant net force assumption needed?Explanation / Answer
1. (a) if acc is constant then
average speed = (vi + vf)/2 = (0 + 8) /2
= 4 m/s
(b) d = v t = 4 x 1.4 = 5.6 m
(c) Yes. it is needed.
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2 . (a) F = k x
1.1 = 40.1 x => x = 0.027 m
L0 = L - x = 0.35 m
(b) then L0 = L + x = 0.41 m