# How to Calculate Momentum and Find Forces in a Collision?

• Messiah19
In summary, a car with a mass of 1000kg and a speed of 10m/s collides with a truck with a mass of 2000kg and a speed of 5m/s in the opposite direction. After the impact, the car moves with a speed of 2m/s in the opposite direction. To calculate the rate of change of momentum during the impact, we use the equation Mv-Mu = 48,000N. According to the law of conservation of momentum, the force that the car exerts on the truck is equal to the rate of change of momentum, which is 48,000N. To find the velocity of the truck after the collision, we use the same equation and solve
Messiah19

## Homework Statement

2:

A car of mass 1000kg moving with a speed of 10m/s has head on collision with a truck of mass 2000kg moving in the opposite direction with a speed of 5m/s. After impact the car moves with a speed of 2m/s in the opposite direction to its original motion.

1 Calculate the rate of change of momentum of the car if the impact lasts for 0.25 sec

2 what is the force that the car exerts on the truck during impact. State the laws.

3 Find the velocity of the truck after collision

## Homework Equations

No equations given

## The Attempt at a Solution

1: Mv- Mu
1000 * 10 - 1000* -2 = 12000/0.25 = 48 000 N

2: For every action there is an equal and opposite reaction so 48000 N

3: don't have a clue :(

Messiah19 said:

## Homework Equations

No equations given

Yes there are. Look up "conservation of momentum" and "impulse".

## The Attempt at a Solution

1: Mv- Mu
1000 * 10 - 1000* -2 = 12000/0.25 = 48 000 N

You've got the units wrong. If you multiply mass times velocity, you get a momentum, not a force. But even after correcting that, it gives you the change $\Delta p$ in momentum. You were asked for the rate of change $\Delta p / \Delta t$ of the momentum.

2: For every action there is an equal and opposite reaction so 48000 N

Again, look up "impulse" in your book.

3: don't have a clue :(

For this one, look up "conservation of momentum" in your book.

Try to implement my advice in another solution attempt. If you're still stuck, then repost.

## 1. What is momentum in mechanical physics?

Momentum is a measurement of an object's motion, taking into account both its mass and velocity. It is a vector quantity, meaning it has both magnitude and direction.

## 2. How is momentum calculated?

Momentum (p) is calculated by multiplying an object's mass (m) by its velocity (v). This can be expressed as the equation p = m x v.

## 3. What is the law of conservation of momentum?

The law of conservation of momentum states that the total momentum of a closed system remains constant, meaning it does not change, unless acted upon by an external force. This means that in any interaction between two objects, the total momentum before the interaction must equal the total momentum after the interaction.

## 4. How is momentum related to force?

Force (F) is defined as the rate of change of an object's momentum. This means that the more force applied to an object, the greater the change in its momentum will be. This relationship is expressed as the equation F = m x a, where m is the object's mass and a is its acceleration.

## 5. Can momentum be negative?

Yes, momentum can be negative. This occurs when an object is moving in the opposite direction of its chosen positive direction. For example, if an object is moving west and its chosen positive direction is east, its momentum would be negative. However, the magnitude of the momentum (its speed) would remain the same regardless of the chosen positive direction.

Replies
10
Views
2K
• Introductory Physics Homework Help
Replies
6
Views
808
• Introductory Physics Homework Help
Replies
6
Views
1K
Replies
7
Views
3K
• Classical Physics
Replies
2
Views
589
• Introductory Physics Homework Help
Replies
1
Views
1K
• Special and General Relativity
Replies
67
Views
4K
• Introductory Physics Homework Help
Replies
1
Views
642
• Mechanics
Replies
29
Views
2K
• Introductory Physics Homework Help
Replies
29
Views
2K