System of particles and rotational motion

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Preethi M S

S N V Skt H S S

N. Paravur

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Q1. In pure translational motion at any instant of time

               all particles of the body have ..............

Answer :  Same velocity

Q2. What is the path of the center of mass of the fragments after explosion of a firecracker?

Answer :   Parabolic

Q3. Which law is used to explain the movement of the fission fragments
 
                  in opposite direction during the disintegration of Radium ? 

Answer :   Conservation of linear momentum

Q4. The rotational analog of force is... 

 Answer :  Torque

Q5. Mechanical advantage of a lever is equal to 1

   

             Then load-arm is ............... effort arm 

Answer :   equal to

Hint:  Mechanical advantage = length of Effort arm / length of Load arm

Q6. .............. is the point on a body where the sum 

                 of the gravitational torque is equal to zero 

Answer :   Center of gravity

Q7. To maintain the rotor at uniform angular speed of 100 rad/s , and engine

          needs to transmit torque of 100 Nm. The power of the engine is ..... 

Answer :   10 kW

Hint: 

 Here, ω= 100 rad/s,       τ = 100 Nm
 Power of the engine, P = τ x ω
 P = (100Nm)  x (100 rad/ s) = 10 x 10³ W = 10kW

Q8. When acrobat bends his body ( assume no external torque ) ...... 

Answer :   Both [A] and [C]

Q9. Two point objects of mass 1.5 g and 2.5 g , respectively are at a distance of 

16 cm apart, the centre of gravity is at a distance x from the object 

  of mass 1.5 g, where x is ..... 

Answer :   10 cm

Hint :

Q10. The theorem of perpendicular axis is applicable for .... 

Answer :   Only planar bodies