# Free fall question, 2 objects meet

In summary: So if you're looking for a work around, you're out of luck.In summary, both objects are in free fall and will meet when their positions are the same.
Gold Member

## Homework Statement

Object A has VA =20m/s going downwards, Object B has VB=20m/s going upwards. Only gravity is given and they are traveling along a straight line vertically. What is the Δt when they meet and what Δd for object B.

## Homework Equations

5 Kinematic equations + v=Δd/Δt,a=Δv/Δt

## The Attempt at a Solution

I've tried numerous ways to approach this problem, I've concluded that they will meet each other when both times are equal to each other but I don't know how to resolve that given the equations I have. I've tried substituting equations, subtracting, using the quadratic formula to no avail. I'm looking at some advice at how I can understand this problem to improve my grasp of physics, I'm not looking for the answer. I've worked at this for about 4 hours and nothing has come from it, any hits/suggestions would be appreciated.

What is their initial position? If they start at the same position they will never meet.
Both are in free fall?

i've concluded that they will meet each other when both times are equal to each other
Their positions are the same as well.
Please show your work, otherwise it is impossible to tell what went wrong.

Object A is above object B that's all the information I have that is given. I can add what work I've tried so far but it will be a lengthy add, if it will help I can do it no problem

If you don't know their initial separation you cannot get a reasonable answer. You can invent a variable and solve using this variable, of course, but that's not the way homework questions are supposed to work.
Can you copy the exact original homework question?

I'm sorry mfb there isn't anything else to copy which is why I came here hoping to find some sort of hint. My teacher just wrote it on a piece of paper the same way I drew it with both velocities and only gravity working with it. It's bonus class work so I'd have to take a photo of it and post it tomorrow but you won't find it any useful.

mfb said:
If you don't know their initial separation you cannot get a reasonable answer. You can invent a variable and solve using this variable, of course, but that's not the way homework questions are supposed to work.
Can you copy the exact original homework question?
The thing is also I haven't done calculus yet and this is a grade 11 physics class so I'm fairly new at this.

Then I don't think the question makes sense.
You can introduce some variable for the initial height difference and find the collision time. Hint: this is very simple with the right idea.
What does Δd even mean?

mfb said:
Then I don't think the question makes sense.
You can introduce some variable for the initial height difference and find the collision time. Hint: this is very simple with the right idea.
What does Δd even mean?
Δd means change df-di, it's the Greek delta sign. I thought about introducing some distance variables but when I don't know the relative position of object A/B i don't understand what i'd find with that? I've used the quadratic equation when I assumed the height was 1 and it didn't get me closer to solving the problem.

mfb said:
Then I don't think the question makes sense.
You can introduce some variable for the initial height difference and find the collision time. Hint: this is very simple with the right idea.
What does Δd even mean?

The

## Homework Equations

[/B]I wasn't given with the question, I added those to the list of equations that I was attempting to use to solve the problem.

Wanted to update you about the question. I threw in the towel finally with the question and while she was explaining to me how to solve the question I mentioned we can't solve it in that manner because we don't have position/displacement. It turns out she made a mistake and forgot to give me that information.

mfb

## What is free fall?

Free fall is the motion of an object under the sole influence of gravity.

## What is the acceleration due to gravity?

The acceleration due to gravity is a constant value of 9.8 meters per second squared, which is the rate at which objects accelerate towards the Earth's surface due to gravity.

## How do two objects meet in free fall?

In free fall, two objects will meet if they are dropped from the same height at the same time, or if one object is dropped and the other is thrown horizontally.

## What factors affect the rate of free fall?

The only factor that affects the rate of free fall is the gravitational acceleration, as all objects will accelerate at the same rate regardless of their mass or shape.

## Can two objects meet at different points in free fall?

Yes, two objects in free fall can meet at different points if they have different initial velocities or are subject to different external forces, such as air resistance.

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