A block is suspended from the ceiling of a lift by a light
PHYSICS · Multi-part · CBSE · Physics · Laws of Motion · Laws of Motion
Problem
A 2kg block is suspended from the ceiling of a lift by a light, inextensible string. The lift, initially at rest, starts moving upward with a constant acceleration of 2ms−2. Take g=9.8ms−2.
(a) Draw a labelled free-body diagram of the block as seen (i) by an observer standing on the ground outside the lift, and (ii) by an observer standing inside the accelerating lift.
(b) For the observer on the ground, calculate the tension in the string while the lift is accelerating.
(c) Show that the observer inside the lift obtains the same numerical value for the tension if an appropriate additional force is introduced in his free-body diagram. Determine the magnitude and direction of this additional force.