Speed of ball dropped from building after falling 2d

[Peter Groppino]

Homework Statement

A ball is dropped from the top of a building and falls vertically downwards. Air resistance can be neglected. After falling a distance d, the speed of the ball is v. Determine the speed of the ball (in terms of v) when it has fallen a distance of 2d.

Homework Equations

The Attempt at a Solution

We tried to isolate for V₂ and d and then substitute them into each other but that didn't work. Please help!

 

[FactChecker]

You should show the relevant equations and what you did with them in your work.

 

[Peter Groppino]

You should show the relevant equations and what you did with them in your work.

I'm sorry but what's a relevant equation? a=9.8m/s² and V₁=0m/s and I'm not sure what to put for d and V₂ which is what we are solving for. Not sure if that helps?

 

[vela]

Can you identify what kind of problem this is, e.g., what concepts are relevant? What do you mean by "university acceleration" in the title? You're referring to $d$, $v_1$, and $v_2$. The variable $d$ is defined in the problem statement, but we'd have to guess what you mean by $v_1$ and $v_2$.

 

[Peter Groppino]

Can you identify what kind of problem this is, e.g., what concepts are relevant? What do you mean by "university acceleration" in the title? You're referring to $d$, $v_1$, and $v_2$. The variable $d$ is defined in the problem statement, but we'd have to guess what you mean by $v_1$ and $v_2$.

Im sorry I am in grade 12 doing a "University" question. I just wrote down what the question asked me. I have no clue what to do. Sorry

 

[PeroK]

Im sorry I am in grade 12 doing a "University" question. I just wrote down what the question asked me. I have no clue what to do. Sorry

Hint: Distance is the area under a graph of speed against time.

 

[jbriggs444]

I'm sorry but what's a relevant equation? a=9.8m/s² and V₁=0m/s and I'm not sure what to put for d and V₂ which is what we are solving for. Not sure if that helps?

We are given information on both the distance fallen and on the final velocity. From that information [and an assumption of constant acceleration] it is possible to write down an expression for the actual acceleration. That acceleration might not be 9.8 m/s².

What are some equations that you know for motion under constant acceleration? Or for work, momentum and kinetic energy?