CameraIcon
CameraIcon
SearchIcon
MyQuestionIcon
MyQuestionIcon
Question

In the shown pulley-block system, strings are light. Pulleys are massless and smooth and system is released from rest. In 0.6 second, what is the work done by gravity on 20 kg and 10 kg block respectively ?
Take [g=10 m/s2]


A
120 J;30 J
No worries! We‘ve got your back. Try BYJU‘S free classes today!
B
30 J;120 J
No worries! We‘ve got your back. Try BYJU‘S free classes today!
C
240 J;60 J
Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses
D
240 J;60 J
No worries! We‘ve got your back. Try BYJU‘S free classes today!
Open in App
Solution

The correct option is C 240 J;60 J
Using constraints, if acceleration of 10 kg is a upwards, acceleration of 20 kg is 2a downwards,

FBD for both bodies

2T10g=10a.....(1)20gT=40a.......(2)

From (1) & (2)

30g=90a
a=g3

Displacement of 20 kg block

=12at2=12×2g3×0.62=1.2 m

Therefore as per the pulley system arrangement
Displacement of 10 kg=1.22=0.6 m

Work done on 20 kg block by gravity
=mgh=20×10×1.2=240 J

Work done on 10 kg block
=mgh2 (moving up)
=10×10×1.22
=60 J

Hence option C is the correct answer

flag
Suggest Corrections
thumbs-up
0
BNAT
mid-banner-image