Question

Two identical blocks A and B are placed on two inclined planes as shown in figure. Neglect resistance and other friction.

Read the following statements and choose options.
Statement I: The kinetic energy of A on sliding to J will be greater than the kinetic of B on sliding to O.
Statement II: The acceleration of A will be greater than acceleration of B when both are released on the inclined plane.
Statement III: The work done by external agent to move the block slowly from position B to O is negative.
A. (a) Only statement I is true
B. (b) Only statement II is true
C. (c) Only I and III are true
D. (d) Only II and III are true

Answer 1

Correct Answer - D
Statement I: Work done by gravity is same for motion from A to J and B to M for equal mass. So KE will be equal.
Statement II: Acceleration `=gsin theta`
`sin theta_Agt sin theta_B=h/lgt(h)/(2l)`
Statement III: `W_g+W_(ext)=0` (Because to block moves slowly)
`W_(ext)=-W_g`
From B to O: `W_g` is positive, so `W_(ext)lt0`.