# Relative velocity and force relationship

• k.udhay
In summary, the collision between two objects can be analyzed by calculating the velocity, momentum, and energy of the objects before and after the collision. However, to determine the force, you must know the time over which the collision took place.

#### k.udhay

This is something related to my job.

There are two components A & B both traveling the same direction but at a different velocity. I can find out the exact velocity of both the components when they just hit each other, thus relative velocity is known.

Is there a way I find out the force exerted during this collision? I know the mass properties (mass & inertia) of A & B.

Pl. help

P.s. - I am aware that force is a function of acceleration (and hence time). However, I am clueless here as what time to be considered.

k.udhay said:
This is something related to my job.

There are two components A & B both traveling the same direction but at a different velocity. I can find out the exact velocity of both the components when they just hit each other, thus relative velocity is known.

Is there a way I find out the force exerted during this collision? I know the mass properties (mass & inertia) of A & B.

Pl. help

P.s. - I am aware that force is a function of acceleration (and hence time). However, I am clueless here as what time to be considered.

If you knew something about the time, you could work out the impulse from the change in momentum and then work out the force from the time over which the collision took place.

You can't solve it without more information. Clearly two water balloons would be in contact with each other for longer than two blocks of steel during similar velocity collisions.

Can you put accelerometers on your components?

This is the sort of question that's often asked in the context of car crashes and personal injuries (punches etc.) and the 'force' of the collision is what people want to know. And it's really hard! To find it, you need to know the details of the structure of the two components because they will deform whilst the momentum is re-arranged between them. It may be that you don't actually need to know those details - unless you are worried about damage - and you can assume a perfectly elastic or totally inelastic collision and that can give you some bounds for the resulting motion.

• k.udhay
@k.udhay If you are able to do some experimenting, you could find the 'spring constant' of the components and treat them as colliding springs. With a bit of ingenuity, you could work out the Potential Energy in the springs during contact and that could tell you the sort of forces acting. Whether it would be worth going into all that would depend on your facilities and technical know how.

• k.udhay
Some objects clearly cannot be compressed more than a certain amount during a collision or damage will occur. You can probably use that to set a lower bound on the forces involved.

## What is relative velocity?

Relative velocity refers to the velocity of an object in relation to another object. It is the difference between the velocities of two objects and can be calculated by subtracting the velocity of one object from the velocity of the other object.

## How does relative velocity affect the force between two objects?

The relative velocity between two objects can affect the force between them. If the relative velocity is zero, there will be no force between the objects. However, if the relative velocity is non-zero, the force between the objects will be affected by the direction and magnitude of the relative velocity.

## What is the relationship between relative velocity and force?

The relationship between relative velocity and force is described by Newton's second law of motion, which states that the force between two objects is directly proportional to the product of their masses and the magnitude of their relative velocity. This means that a greater relative velocity between two objects will result in a greater force between them.

## How does the angle of relative velocity affect the force between two objects?

The angle of relative velocity between two objects can affect the force between them. If the angle is perpendicular, the force will be at its maximum. If the angle is parallel, the force will be at its minimum. This is because the component of relative velocity in the direction of the force is what determines its magnitude.

## Can relative velocity and force be negative?

Yes, relative velocity and force can be negative. This simply means that the objects are moving in opposite directions, which will result in a negative value for their relative velocity and force. It is important to consider the direction of motion when using these values in calculations.