Question

A uniform rod of mass 2kg and length 1m is lying on a horizontal surface the work done in rising one end of the rod through an angle 45 degree isW,the work done in raising the further through 45 degree

Answer 1

Answer:

3W

Explanation:

given,

work done in rising the rod from 0 to π/4 =W

now,

we know that ∫du=F∫dθ(limits 0 to π/4)

                          U=F[θ²/2]

                          U=F[π²/32]→this is W

similarly for further lifting of rod from π/4 to π/2

apply the above process again,

∫du=F∫dθ(limits π/4 to π/2)

U=F[θ²/2]

U=F[3π²/32]

or

U=3F[π²/32]⇒3W

here from the first solutionF[π²/32]=W

(if you want numerical solution put F=mg⇒20,π=3.14)