Momentum and Conservation Principles

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Questions and Answers

What is the final velocity of the 4 kg block after its collision with a 6 kg block moving at 8 m/s?

2.5 m/s

2 m/s

-2 m/s (correct)

0 m/s

In the collision between a 10,000 kg engine and a 5,000 kg car, what is their common velocity after locking together?

1.5 m/s

3.33 m/s

2.66 m/s (correct)

4 m/s

If the momentum before a collision is 40,000 kg m/s, what is the result of the equation for momentum conservation if the total mass after the collision is 15,000 kg?

v = 2.66 m/s (correct)

v = 4 m/s

v = 1.75 m/s

v = 3 m/s

What happens to the momentum of the piñata when it is struck by a child with a stick?

It increases Signup and view all the answers

What is the key principle that governs the interactions between objects in a collision?

Momentum is conserved Signup and view all the answers

When a gun fires a bullet, what is observed regarding the gun's motion?

The gun recoils backwards Signup and view all the answers

Why are moving objects difficult to stop?

They contain momentum Signup and view all the answers

If the bullet fired from a gun has a mass of 15 grams and a velocity of 500 m/s, what effect does this have on the gun's motion?

The gun moves in the opposite direction to the bullet Signup and view all the answers

What is the correct formula for calculating momentum?

p = mv Signup and view all the answers

Which of the following quantities does NOT affect the momentum of an object?

Change in temperature Signup and view all the answers

If a 1200 kg train moves west at 20 m/s, what is its momentum?

24,000 kg m/s West Signup and view all the answers

In a collision, if no external forces act on the objects, what does the Principle of Conservation of Momentum state?

Total momentum before equals total momentum after the collision. Signup and view all the answers

How can the momentum of a body change?

Through a change in mass, speed, or direction Signup and view all the answers

In the equation for conservation of momentum, m1u1 + m2u2 = m1v1 + m2v2, what do u and v represent?

u represents initial velocities and v represents final velocities Signup and view all the answers

What would be the momentum of a system of two colliding objects if their total initial momentum is 50 kg m/s?

50 kg m/s Signup and view all the answers

If a 4 kg block moving at 10 m/s collides with a stationary 6 kg block, which of the following is true after the collision?

The total momentum will be conserved. Signup and view all the answers

Study Notes

Momentum

Momentum (p) is the resistance to a change in motion of an object.
The momentum of an object is calculated as: p = mv, where m is mass and v is velocity.
Momentum is a vector quantity; it has both magnitude and direction.
Momentum of an object will never change unless an external force is applied.
Momentum can change due to:
- Change in mass
- Change in speed
- Change in direction

### Principle of Conservation of Momentum

The Principle of Conservation of Momentum states that in a closed system, the total momentum before an interaction equals the total momentum after the interaction.
This principle is applicable for collisions and explosions.
Mathematically, the conservation of momentum can be represented as:
- m1u1 + m2u2 = m1v1 + m2v2
- m1, m2 are the masses of the objects.
- u1, u2 are the initial velocities.
- v1, v2 are the final velocities.

Momentum Problems

Example: A 10,000 kg train moving at 4 m/s collides with a stationary 5,000 kg train car.
The two trains lock together. Momentum before the collision equals momentum after.
Before collision: 10,000 kg (4 m/s) + 5,000 kg (0 m/s) = 40,000 kg m/s
After collision: (10,000 kg + 5,000 kg) v = 40,000 kg m/s
The final velocity is calculated as v = 40,000 kg m/s / 15,000 kg = 2.66 m/s

Momentum in Gun Firing

When a gun is fired, the momentum before is zero because both the gun and the bullet have zero velocity initially.
Momentum is conserved:
- mgug + mbub = mgvg + mbvb
- mg is the mass of the gun.
- mb is the mass of the bullet.
- ug, ub are the initial velocities.
- vg, vb are the final velocities.
Since the initial velocities are zero, 0 = 4vg + 15x10-3 (500)
The gun's final velocity is calculated as vg = -1.875 m/s
The negative sign indicates the gun travels in the opposite direction of the bullet.

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Description

Test your knowledge on the concepts of momentum and the principle of conservation of momentum. This quiz covers key definitions, calculations, and examples of momentum in action, including its vector nature and applications in collisions. Discover how changes in mass and velocity affect momentum.