Question

A particle oscillating simple harmonically with an amplitude 1.5cm

Answer 1

We assume zero friction loss and zero air resistance. Further we assume that the string is light and inextensible. These assumptions (especially the ones about the string) may seem trivial but actually are important assumptions.

At either of the extreme positions of the pendulum, the Kinetic Energy (KE) = 0 while the Potential Energy (PE) = maximum. Let us call the extreme positions as E1 and E2 and the centre position as C.

Assuming for the sake of the argument that the pendulum bob is taken to position e1 and released with zero initial speed. Under gravity, the pendulum moves to C, then to E2, then back to C, then again E1, then again C and so on......

The above E1-C-E2-C-E1 is one cycle.

As you can see, the KE goes from zero (at E1) to max (at C) then again to zero (at E2) then again to max (at C).