Originally Posted by **r.samanta** the problem is for a different planet, whose g is less. On earth , it would take less time to fall.(1.4 seconds to be precise) |

Okay but that's how the question was given to us, how are we supposed to know if the planet is earth or some other planet? I mean, it shouldn't matter what planet you are on, the formulas work the same, unless the value of gravity given is different than 9.81/10 or it's mentioned in the question that the question is related to such and such planet. I mean these kind of questions are quite basic and they don't require us to first calculate if the question or value of gravity is based on earth or some other planet and then solve the rest of the questions accordingly.

For example another question which was given to us is as follows:

Q) A ball is dropped from a height of 20 m. It bounces back with 3/4th speed, with which it hits the ground. Calculate:

a) Final velocity with which it hits the ground first time.

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In this question I get the correct answer when I take the Acceleration to be 9.81. You see what I mean? Here I didn't even have to calculate the value of Acceleration first because I thought it's a freely falling object so it's acceleration must be 9.81. And I was correct, it gives the correct answer.

Now this question is quite similar to the first question, then why did we have to calculate a value for acceleration in the first one, which is obviously a different value than the value in this question.

I'm so confused!