Question

the mass of a uniform copper bar varies directly as its length. if a bar 40cm long has a mass of approximately 420g. find the mass of a bar 136cm long?.

Answer 1

hi mate to solve this question , take a small length of rod dx ,which mass is assume dm

according to question mass is directly proportional to length .Therefore make an equation


dx = dm

now integrate both side and then put limit of x 40 to 136 and limit of m 420 to M


after solve it you will find M = 516 g , which is mass of rod at 136 cm....



I hope you are understand it very well