Question

How could a $10kg$ object be lowered down from a height using a cord with a breaking strength of $80N$ without breaking the cord?

• A. By lowering the object very slowly
• B. By lowering it with an acceleration less than $2m/s^2$
• C. By lowering it with an acceleration greater than $2m/s^2$
• D. Object cannot be lowered down without breaking the cord

Answer 1

Answer: (C)

By lowering it with an acceleration greater than $2m/s^2$

Given maximum tension in the string can be 80 newtons.
Now, by applying newtons law on the block we have
$mg-80=ma$
$a=2m/s^2$

so, for other cases, $T=mg-ma$

So, $a$ needs to be greater than $2m/s^2$