Motion

(1) True - always = -g
(2) True - as PE + KE = constant and no loss due to air resistance
(3) not true - as external force of gravity is acting on it

(1) True
air resistance is negligible, so the acceration is only due to the acce due to gratity.,pointing to the ground (9.81 m per s )
(2) True
When the stone move upwards KE turn to PE
At highest point , KE is 0 and PE max.
When falling dwn, PE turn back to KE.
(3)False
monentum =mass x velocity Since KE of the motion is changing thoughtout the jounrey , the vaiue of monentum varies .
Note if air resi is counted ,then the acc is decreasing thoughout ,
When moving up, ,
Air Resistance and g are in same dir ( Net a =g+r)
Highest pt (Net a=g)
When moving down
r and g are opposite dir , but g.>r
Net a =g-r