AS Level Mechanics Question

If an object is projected vertically upwards, can we take its acceleration to be 9.8 and if so why?
i understand that an object falling down has acceleration 9.8 due to it acting under the acceleration of gravity, which is 9.8, but when it it going upwards then wouldn't it be working against gravity making it have a completely different acceleration?

Edit: nvm someone explained it to me but idk how to delete the post
(edited 1 month ago)
Original post by Dhshsnsksnskxn
If an object is projected vertically upwards, can we take its acceleration to be 9.8 and if so why?
i understand that an object falling down has acceleration 9.8 due to it acting under the acceleration of gravity, which is 9.8, but when it it going upwards then wouldn't it be working against gravity making it have a completely different acceleration?
Edit: nvm someone explained it to me but idk how to delete the post

Let's take upwards as positive ( this is the standard) then as the object will decelerate ( or in otherwords acceleration is downwards) we must have acceleration to = -9.81m/s^2. Btw the fact that it has an upward velocity has no impact on the sign of the acceleration... it is how you define you axis that matter.
Original post by Mr Naga Physics
Let's take upwards as positive ( this is the standard) then as the object will decelerate ( or in otherwords acceleration is downwards) we must have acceleration to = -9.81m/s^2. Btw the fact that it has an upward velocity has no impact on the sign of the acceleration... it is how you define you axis that matter.

Thank you