- #1

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- Homework Statement
- Find height of a building

- Relevant Equations
- s= ut + 1/2 at^2

v=u +at

Hi, I have this kinematics question I am struggling with. There is a building from which a ball is dropped and it takes 5 second to reach the ground. Then they say that the same building is on a planet w/o atmosphere where g= 6 m/s^2 . What is the height of the building ?

I approached this question like I approach every other projectile motion questions but the problem here is that I don't have enough information to solve this problem. For the ball being dropped on earth, we only have the time it takes to hit the ground , that's it. There is air resistance acting on the ball so acceleration won't be 10m/s^2. I get this equation for the first using the equation s= ut + 1/2 at^2 => s= 25/2 a . I am assuming the ball is dropped from rest in both cases.

For the second case, where the ball is dropped from the same building but in a planet w/o atmosphere I get using the same equation , s= 3t^2. Here we are given a=6 and because it has no atmosphere, there is no air resistance.

s is the same so I can get = > 25/2a = 3t^2 . Now it's cleat that we need more information, there are 2 variables in the equation and I can't think of any other equation.

I approached this question like I approach every other projectile motion questions but the problem here is that I don't have enough information to solve this problem. For the ball being dropped on earth, we only have the time it takes to hit the ground , that's it. There is air resistance acting on the ball so acceleration won't be 10m/s^2. I get this equation for the first using the equation s= ut + 1/2 at^2 => s= 25/2 a . I am assuming the ball is dropped from rest in both cases.

For the second case, where the ball is dropped from the same building but in a planet w/o atmosphere I get using the same equation , s= 3t^2. Here we are given a=6 and because it has no atmosphere, there is no air resistance.

s is the same so I can get = > 25/2a = 3t^2 . Now it's cleat that we need more information, there are 2 variables in the equation and I can't think of any other equation.

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