Question

Consider a block sliding down a frictionless inclined plane with acceleration a . If we double the mass of the block, what is its acceleration?

• A. a /4
• B. a /2
• C. a
• D. 2a
• E. 4a

Answer 1

Answer: (C)

a

If we resolve weight of block $mg$ into its rectangular components , we see that component , downwards normal to the inclined plane ($mg\cos \theta$) balances the normal reaction of plane on block .On the other hand , component of weight ($mg\sin \theta$) provides the force to the block to slide down on inclined plane ,

as force $F=ma=mg\sin \theta$ , (where $\theta$ is the angle of inclination of the plane to horizontal)

or $a=g\sin \theta$

it is clear that acceleration $a$ doesn't depend upon mass of block , therefore it will remain constant as $a$ .