Most Important Selected Qs for JEE AdvancedPhysicsLaws of Motion
A block of mass m(=0.1 kg ) is hanging over a frictionless light fixed pulley by an inextensible string of negligible mass. The other end of the string is pulled by a constant force F in the vertically downward direction. The linear momentum of the block increases by 2 kgms ⁻¹ in 1 s after the block starts from rest. Then, (given g=10 ms ⁻² )
Options
- AThe tension in the string is F
- BThe tension in the string is 3 N
- CThe work done by the tension on the block is 20 J during this 1 s
- DThe work done against the force of gravity is 10 J
Correct answer
D. The work done against the force of gravity is 10 J
Step-by-step solution
The free body diagram F=2+m g=3 N also, a= unbalanced force mass = 2 0.1 =20 m / s ² S= 1 2 a t²= 1 2 20 1=10 m Honce, work done by tension =F 10=3 10=30 J So, the work done against gravity =m g S=1 10=10 J