Answer:
So length of pendulum is 143.129 m
Explanation:
We have given period of simple pendulum is 2 sec
We have to find the length of simple pendulum
Let the length of pendulum is l
Acceleration due to gravity
is
Time period is given by 
So 

Squaring both side

l =143.129 m
So length of pendulum is 143.129 m
A.What is the effect of air resistance on the cannonball? It's a question related to science and the experiment, which may pop into your head.
Answer:
A : A restoring force acts on an object in simple harmonic motion that is directed in the same direction as the object's displacement.
Explanation:
Statement A is the false one:
A : A restoring force acts on an object in simple harmonic motion that is directed in the same direction as the object's displacement. --> FALSE. The restoring force in the simple harmonic motion is given by

where
k is the spring constant
x is the displacement of the system, measured with respect to the equilibrium position
As we can notice from the equation, there is a negative sign in front of (kx): this means that the force, F, and the displacement, x, have opposite directions. In fact, the restoring force of a simple harmonic oscillator always acts to restore the equilibrium position, therefore it acts in the opposite direction as that of the displacement.