# Find the Velocity of car A before the collision?

• theemassive1
In summary, the problem involves two bumper cars with equal masses colliding elastically, where one car is initially at rest and the other has a velocity of 0.8 m/s 30 degrees north of east. The resulting velocities of the cars after the collision are 0.6 m/s 60 degrees south of east and 0.8 m/s 30 degrees north of east. To find the velocity of car A before the collision, we use the conservation of momentum equation and solve for the unknowns. If the collision were inelastic, the problem would change as the final velocities of the two cars would not be equal to their initial velocities.

#### theemassive1

Bumper cars A and B each have a mass of 100 kg. Bumper car A collides ealstically with bumper car B, which is at rest. After the Collision, the velocity of car A is 0.8 m/s 30degress north of east and car B is 0.6 m/s 60degrees south of east.

1 Find the Velocity of car A before the collision?
2. How would the problem change in the collision were inelastic?

can sum1 please tell me where to even begin here, I am completely lost.

Hi, theemassive1! Welcome to PF. Please note that there is a sub-forum especially for homework help. See https://www.physicsforums.com/forumdisplay.php?f=35 [Broken] . (But don'r repost there, the moderators will move your thread if they feel the need.)

What you've got here is a conservation of momentum problem. The core equation is

$$\sum_{k=A}^B \vec{p}_k^{initial} = \sum_{k=A}^B \vec{p}_k^{final}$$

where the $\vec{p}_k^{initial}$ are the momentum vectors of the bumber cars right before the collision, and the $\vec{p}_k^{final}$ are the momentum vectors of the bumber cars right after the collision. So after you've set up this equation and chosen a practical coordinate system (the standart is to take the y-axis pointing south), the physics is over and all that remains to do is sort out the math: you know how to add vectors and you know that vectors are equal iff their components are equal. So solve for the unknowns: the x and y components of the velocity of A before collision.

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ok, i got it now, thanks alot

## 1. How is velocity calculated?

Velocity is calculated by dividing the change in position (displacement) by the change in time. It is a vector quantity, meaning it has both magnitude (speed) and direction.

## 2. What is the equation for calculating velocity?

The equation for velocity is v = Δx/Δt, where v is the velocity, Δx is the change in position, and Δt is the change in time.

## 3. Is velocity the same as speed?

No, velocity and speed are not the same. Velocity includes the direction of motion, while speed only measures the magnitude of motion.

## 4. How do you find the velocity of a car before a collision?

To find the velocity of a car before a collision, you will need to know the position of the car before the collision, the position of the car after the collision, and the time it took for the collision to occur. You can then use the equation v = (xf - xi)/t to calculate the velocity.

## 5. Can velocity be negative?

Yes, velocity can be negative. A negative velocity indicates that the object is moving in the opposite direction of its positive velocity. For example, if a car is moving west with a velocity of 20 m/s, a negative velocity of -20 m/s would mean the car is now moving east.