An object is allowed to fall freely near the surface of an unknown planet. the object falls 72 meters from rest in 4.0 seconds. the acceleration due to gravity on that planet is

Acceleration due to gravity on that planet, a = 9 m/s²

Explanation:

Initial velocity, u =  0 m/s

Acceleration due to gravity , a = ?

Displacement, s = 72 m

Time , t = 4 s

We have equation of motion s= ut + 0.5 at²

Substituting

   s= ut + 0.5 at²

    72 = 0 x 4 + 0.5 x a x 4²

   a = 9 m/s²

Acceleration due to gravity on that planet, a = 9 m/s²

half of a circle

explanation:

the arrow and the top of the circle is matching together. it is not a polygon because a polygon would always be the same shape. therefore, an half of a circle is called semicircle so you would find the radius of it.

diagram is missing, but i will try to explain your doubt.

answer:

amplitude is the maximum displacement or distance moved on a point of a vibrating body or wave measured from its equilibrium position.it is equal to half the length of vibration path.