# Motion problem with two rocks being released at different times

• mjolnir80
In summary: Yes, Vi for the first rock should be -3 m/s, as the balloon is rising at 3 m/s and the rock is released with no initial velocity. In summary, the problem is to calculate the initial velocity of the second rock, with respect to the ground, given that two rocks are released from a balloon rising at 3 m/s. The first rock is released when the balloon is 50m above the ground, and the second rock is thrown towards the ground 2 seconds later. Both rocks hit the ground at the same time. The method used involves calculating the time it takes for the first rock to hit the ground, subtracting 2 seconds from that time, and using it to calculate the initial velocity of
mjolnir80

## Homework Statement

the question is like this :you are in a balloon that is rising at a rate of 3.0m/s . you have two rocks. you release one when you are 50m above the ground. 2 seconds later you throw the other rock towards the ground . the two rocks hit the ground at the same time . what was the initial velocity of the second rock (with respect to the ground)

## Homework Equations

we have to solve it only using the simple motion equations such as:
∆d = Vi t + ½ a t2

## The Attempt at a Solution

what i did was to first say that :

t(rock1)=t(rock2)-2s and we also know that the second rock is released when we are 56m above the ground

then i proceeded to calculate the time it takes for the first rock to hit the ground (considering the fact that Vi for the first rock is 0)

then i subtracted 2 from this time and used it to calculate Vi for the second rock
i used ∆d = Vi t + ½ a t2 to calculate both these things

the problem is I am not sure I am doing this right and i would appreciate it if someone could confirm my method

that Vi for the first rock is 0
Surely -3 m/s ? The rocks will be moving with the balloon until they are dropped or thrown.

Apart from that your method looks OK.

Last edited:
Mentz114 said:
Surely -3 m/s ? The rocks will be moving with the balloon until they are dropped or thrown.

Apart from that your method looks OK.

oops i was thinking about a different problem

## What is the motion problem with two rocks being released at different times?

The motion problem with two rocks being released at different times involves calculating the distance, velocity, and acceleration of two rocks dropped from different heights at different times and determining when they will meet.

## What is the formula for solving this motion problem?

The formula for solving this motion problem is d = 0.5at² + v₀t + d₀, where d is the distance, a is the acceleration, t is the time, v₀ is the initial velocity, and d₀ is the initial distance.

## How do you determine the acceleration of the rocks?

The acceleration of the rocks can be determined by using the formula a = (v-v₀) / t, where v is the final velocity and v₀ is the initial velocity.

## Can this motion problem be solved using the same formula for both rocks?

Yes, this motion problem can be solved using the same formula for both rocks as long as the initial conditions (height and time) and acceleration are known for each rock.

## Is there a specific method for solving this type of motion problem?

The most common method for solving this type of motion problem is using the kinematic equations, which involve setting up and solving equations based on the known values and unknowns for the motion of the two rocks.

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