Question

A uniform plank is resting over a smooth horizontal floor and is pulled by applying a horizontal force at its one end. Which of the following statements are not correct?
A. Stress developed in plank material is maximum at the end at which force is applied and decreases linearly to zero at the other end.
B. A unifrom tensile is developed in the plank material.
C. since plank is a pulled at one only plank starts to accelerate along direction of the force. Hence no stress is developed in the plank material.
D. Stress at the ends is the same but it changes in between.

Answer 1

Correct Answer - B::C::D

Let mass of the plank is `M` and force `F` is applied as shown. Then at a distance `x` from the other end
`T = (M)/(L) xx x xx (F)/(M) = (x)/(L) F`
Hence stress is `(T)/(A) = (F)/(AL) xx x`
`:.` only option (A) is correct.