It depends on the projected body. If the body is projected against gravity I.even., if the body is vertically projected, then gravity will be -9.8 and if the body is freely falling, then the gravity will be taken as +9.8.
Hope it helps you..
but in some books it was taken as only -9.8 but not +9.8 and also in some books it was with opp. signs
yaa thats because of direction
if the body travels upwards that is against gravity we have to take negative sign, if the body is travelling towards earth i mean downwards thn we hv to take positve sign
When a body or an object is falling freely ,we should conisider the acceleration due to gravity as +9.8 m/s and when is body is thrown vertically upwards,we should consider it to be -9.8 m/s.