JEE Main202227 Jul 2022Evening ShiftPhysicsLaws of MotionActual
A block A takes 2 s to slide down a frictionless incline of 30 ° and length l , kept inside a lift going up with uniform velocity v . If the incline is changed to 45 ° , the time taken by the block, to slide down the incline, will be approximately:
Options
- A2 . 66   s
- B0 . 83   s
- C1 . 68   s
- D0 . 70   s
Correct answer
C. 1 . 68   s
Step-by-step solution
As per the information given in the question the lift is moving upward with uniform velocity. Therefore, the frame of reference attached to the lift is an inertial frame of reference. The acceleration of the block down the incline will be, a = g sin θ Using equation of motion for constant acceleration, s = u t + 1 2 a t 2 ⇒ l = 1 2 g sin 30 ° 2 2               . . . 1 When the inclination is changed to 45 ° , l = 1 2 g sin 45 ° t 2       &#