# Need help with two questions - velocity and momentum?

• Renue
In summary: It is not really worth the effort to try to figure it out unless you are being graded on it.In summary, the first question asks when two balls, one rolling on a flat surface and one rolling on an inclined surface, will have the same velocity. The answer provided is that the velocity will be the same when the gap between the balls is the same at a specific time. The second question is unclear, but it seems to be asking whether the distance between two people playing catch will increase, decrease, or remain the same over time. However, without more information, it is difficult to determine the answer. The concept of speed and velocity is mentioned, but it is not clear how it relates to the questions.
Renue

## Homework Statement

Q1. A ball is rolling on a flat surface and another ball rolling on an inclined surface. When do both the balls have same velocity?
Q2. When two people throw a ball and catch for a period of time, will the distance between them increase, decrease, or remain the same?

## Homework Equations

Q1. No equations or numbers given - just t1, t2, etc.
Q2. This is also a conceptual question and no equations or numbers given.

## The Attempt at a Solution

Q1. I looked at the space between each ball as it is rolling, wherever the gap was same, I chose that time period as having same velocity.
Q2. The distance would remain the same if the velocity is constant throughout.
Please let me know if my thinking is in the right direction for both these questions. Thanks.

Renue said:
I looked at the space between each ball as it is rolling, wherever the gap was same, I chose that time period as having same velocity.
What is the difference between speed and velocity?

Q2 is unclear.

Speed does not have direction (scalar) and velocity is a vector quantity. How do I use this to solve Q1?

I'm sorry for being unclear on Q2, as I am also unclear as to what the question is asking. All I know is - two people are playing throw and catch with a ball for sometime (no time given, no velocity given). Would the distance between these two players, increase, decrease, or remain the same. I'm still confused:-(

Renue said:
wherever the gap was same
Same as what? Do you mean when the gap is at a minimum or maximum?
Renue said:
rolling on an inclined surface
This is possibly ambiguous. It might mean down an inclined surface, or it really might be allowing any direction.
Renue said:
When two people throw a ball and catch for a period of time, will the distance between them increase, decrease, or remain the same?
Is that the exact wording? Is it a translation?
Renue said:
Speed does not have direction (scalar) and velocity is a vector quantity. How do I use this to solve Q1?
it changes the requirement. If the velocity is to be the same then both the speed and direction (in three dimensions) must be the same.

Last edited:
Renue said:
Q2. When two people throw a ball and catch for a period of time, will the distance between them increase, decrease, or remain the same?
I cannot see how this is a scientific question in the absence of any other information.

Renue said:
When two people throw a ball and catch for a period of time, will the distance between them increase, decrease, or remain the same?
Here's a guess: someone forgot to mention that they are standing on frictionless ice, perhaps?

Question 2 is a bit vague as it depends on whether static friction is present.

However, if friction is not present then try to think about the change experienced by the persons when catching the ball as well as throwing the ball.

Kaura said:
However, if friction is not present then try to think about the change experienced by the persons when catching the ball as well as throwing the ball.
Even if friction is not present it is a vague question - it does not give you the initial condition nor any qualifier for what "some time" means.

## 1. What is the difference between velocity and momentum?

Velocity refers to the speed and direction of an object's motion. It is a vector quantity, meaning it has both magnitude and direction. Momentum, on the other hand, is a measure of an object's mass and velocity. It is also a vector quantity and is defined as the product of an object's mass and velocity.

## 2. How do you calculate velocity?

Velocity is calculated by dividing the displacement of an object by the time it took to travel that distance. The formula for velocity is v = d/t, where v is velocity, d is displacement, and t is time.

## 3. What is the unit of measurement for velocity?

The unit of measurement for velocity is meters per second (m/s) in the SI system. In other systems, it may also be measured in feet per second (ft/s) or kilometers per hour (km/h).

## 4. Why is momentum important?

Momentum is important because it is a conserved quantity in a closed system. This means that in the absence of external forces, the total momentum of a system remains constant. It also helps us understand the behavior of objects in motion and plays a crucial role in many areas of science, such as mechanics, thermodynamics, and electromagnetism.

## 5. Can an object have momentum without having velocity?

No, an object cannot have momentum without having velocity. Velocity is a necessary component of momentum, and without it, an object cannot have any momentum. However, an object can have velocity without having momentum if its mass is zero, as momentum is directly proportional to an object's mass.

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