Question

if the simple pendulem of length l has maximum angular displacement thita the maximum kinetic energy of bob of mass m is

Answer 1

The M will remain Same

Answer 2

Use L for length to avoid confusion with (eye) or (one) 

If θ is measured from vertical, then at the point where the mass has no velocity, it will have maximum potential energy. 

The maximum kinetic energy found when the mass is at the lowest point (angle of 0) will equal the mass gravity potential energy at angle of θ 

The height the mass has risen is found via geometry 

At the lowest point, the mass is a distance L below the pivot center 
At angle θ, the mass is a distance of Lcosθ below the pivot center 
The change in height h is the difference between these 

h = L - Lcosθ 
h = L(1-cosθ) 

KE = PE = mgh 
KE = mgL(1 - cosθ) 

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