Laws of Motion

© examsnet.com
Question : 33
Total: 40
A monkey of mass 40 kg climbs on a rope as shown in the figure which can stand a maximum tension of 600 N. In which of the following cases will the rope break: the monkey
(a) climbs up with an acceleration of 6 m s2
(b) climbs down with an acceleration of 4 m s2
(c) climbs up with a uniform speed of 5 m s1
(d) falls down the rope nearly freely under gravity?
(Ignore the mass of the rope).
Solution:  
Here, mass of monkey m=40 kg
Maximum tension the rope can stand, T=600 N.
In each case, actual tension in the rope will be equal to apparent weight of monkey (R).
The rope will break when R exceeds T.
(a) When monkey climbs up with a = 6 m s2,
R=m(g+a) =40(10+6)=640N (which is greater than T)
Hence the rope will break.
(b) When monkey climbs down with a = 4 m s2,
R=m(ga) =40(104)=240N (which is less than T)
∴ The rope will not break.
(c) When monkey climbs up with a uniform speed v= m s1, its acceleration a=0
R=mg=40×10=400N (which is less than T)
∴ The rope will not break.
(d) When monkey falls down the rope nearly freely under gravity,
a=g
R=m(ga)=m(gg)= zero
Hence the rope will not break.
© examsnet.com
Go to Question: