11) As shown in the figure, two blocks we connected by a very light string, and
ID: 1320838 • Letter: 1
Question
11) As shown in the figure, two blocks we connected by a very light string, and the upper block is pulled upward by a different string The masses of the upper end lower blocks are 300 g and 240 g, respectively. The string between the blocks will break if its tension exceeds 3.6 N, and the string that pulls the combination on upward will break if its tension exceeds 7.8 N. (a) What is the largest upward acceleration that the blocks can be given without either string breaking? (b) If the upward acceleration is slightly higher than this, which string breaks, the upper one or the lower one?Explanation / Answer
a) suppose system is pulled by T tesnion in upper string
then T - mg = ma
T - (0.300 + 0.240)g = (0.300 + 0.240)a
a = (T -0.540g) / 0.540
if max. value of T is used then,
a = 7.8 - 0.540g / 0.540 = 4.63 m/s2
now balancing forces in vertical on lower block,
TL - 0.240g = 0.240a
using max. values then TL will be :
TL = 0.240(4.63+ 9.81) = 3.47 N that is under limit.
so , a = 4.63 m/s2 ...........Ans
now from this solution we see that upper string is just on limit value but lower string is not.
if we exceed acc. by a small amount then upper string break.
so upper string will break first......Ans
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.