B: Physics = Changes in Motion 2.5 Conservation of Momentum Flashcards
What is forensic engineering?
A special branch of engineering that answers questions related to accidents.
What methods do forensic engineers use to investigate collisions?
Collecting data from photographs, inspecting the damaged vehicle, and measuring damage.
What role does momentum play in investigating motor vehicle collisions?
It helps determine the likely velocity of each vehicle before and after the collision.
Fill in the blank: Forensic engineers may use _______ to piece together the speed of the car before the accident.
[accident-reconstruction software].
What do investigators calculate to determine the speed of vehicles involved in a collision?
The total momentum of the vehicles before and after the collision.
What are the three basic types of collisions?
- Hit and rebound
- Hit and stick
- Explosion
What is the law of conservation of momentum?
The momentum gained by one object equals the momentum lost by another, keeping the total momentum constant
What does the Greek letter sigma (Σ) represent in the context of momentum?
The phrase ‘the sum of’
In the context of momentum, what does the equation state?
The sum of the momentum before the interaction equals the sum of the momentum after the interaction
True or False: Momentum can be transferred from one object to another.
True
Fill in the blank: The law of conservation of momentum states that if the net force acting on a system is ______, the sum of the momentum before an interaction equals the sum of the momentum after the interaction.
zero
How can quantities after an interaction be indicated in equations?
By using the prime symbol (‘)
A 10 000 kg freight car travelling west with a velocity of 1.5 m/s collides with a 20 000 kg freight car at rest. After the collision, the freight cars stick together. Determine the velocity of the freight cars after the collision.
What is the mass of the freight car that is travelling west in the example problem?
10,000 kg
A 10 000 kg freight car travelling west with a velocity of 1.5 m/s collides with a 20 000 kg freight car at rest. After the collision, the freight cars stick together. Determine the velocity of the freight cars after the collision.
What is the velocity of the 10,000-kg freight car before the collision?
1.5 m/s
A 10 000 kg freight car travelling west with a velocity of 1.5 m/s collides with a 20 000 kg freight car at rest. After the collision, the freight cars stick together. Determine the velocity of the freight cars after the collision.
What is the mass of the freight car that is at rest before the collision?
20,000 kg
A 10 000 kg freight car travelling west with a velocity of 1.5 m/s collides with a 20 000 kg freight car at rest. After the collision, the freight cars stick together. Determine the velocity of the freight cars after the collision.
What happens to the freight cars after the collision in the example problem?
They stick together
What is the consequence of a collision in one-dimensional space?
The collisions occur in a straight line
What is the total amount of momentum in a closed system during a collision?
It remains constant
A 10 000 kg freight car travelling west with a velocity of 1.5 m/s collides with a 20 000 kg freight car at rest. After the collision, the freight cars stick together. Determine the velocity of the freight cars after the collision.
The freight cars have a velocity of 0.50 m/s [W] after the collision.
Sum of momentum before = sum of momentum after
so p1 + p2 = p1and2
10 000 kg (-1.5 m/s) = 30 000 kg (v1and2)
What is meant by a one-dimensional collision?
A collision that occurs along a single line or direction.
Describe the law of conservation of momentum in your own words.
If the net force acting on a system is zero, the total momentum before an interaction equals the total momentum after the interaction.
True or False: The law of conservation of momentum applies only to two-dimensional problems.
False
Fill in the blank: The law of conservation of momentum states that if the net force acting on a system is ______, the momentum before an interaction equals the momentum after the interaction.
zero
