3.5 Newton’s laws of motion and momentum Flashcards
3.5.1 Newton’s laws of motion, 3.5.2 Collisions, (32 cards)
What does the conservation of momentum state?
The total momentum before two objects collide is the same as the total momentum after they collide.
In a collision where two objects do not stick together, what is the equation for conservation of momentum?
m₁u₁ + m₂u₂ = m₁v₁ + m₂v₂
What does the equation m₁u₁ + m₂u₂ = mv represent?
It represents a collision where two objects stick together.
In the context of explosions, what is the equation for momentum?
mu = m₁V₁ + m₂V₂
What does ‘impulse’ refer to in physics?
Impulse is defined as the force multiplied by the time for which the force acts.
What is the relationship between impulse and change in momentum?
Impulse is equal to the change in momentum that it causes.
How do you calculate change in momentum when dealing with vectors?
change in momentum = (-m₁y) – (m₁u)
What is conserved in elastic collisions?
Total energy, including kinetic energy, is conserved.
What happens to kinetic energy in inelastic collisions?
Kinetic energy is not conserved; it is less after the collision than before.
What characterizes a perfectly inelastic collision?
The maximum amount of kinetic energy is lost, and objects stick together after the collision.
In the context of explosions, what happens to the kinetic energy of the pieces?
The total kinetic energy of the pieces after an explosion is more than before it explodes.
What safety features help reduce the force of an impact by increasing the time for momentum to change?
- Air bags
- Seat belts
- Crumple zones in cars
- Cycle helmets
- Cushioned surfaces in children’s playgrounds
- Packaging for fragile items
What does the area under a force-time graph represent?
The impulse of the force, or the change in momentum of the object.
True or False: The peak force in a force-time graph with safety features is higher than without.
False
In a force-time graph with safety features, what happens to the area under the graph?
The area remains the same.
Fill in the blank: The total kinetic energy of the objects involved in an elastic collision is the same ______ the collision.
before
What is the formula for momentum?
p = mv
p represents momentum, m is mass, and v is velocity.
Momentum is a _______ quantity.
vector
Momentum has both magnitude and direction.
According to the principle of conservation of momentum, the total momentum of a system remains _______.
constant
This holds true as long as no net external force acts on the system.
What does Newton’s second law state?
F = ma
F is net force, m is mass, and a is acceleration.
If there is no net external force acting on an object, it will _______.
not accelerate
This follows from Newton’s first law.
The unit of momentum is _______.
kg·m/s
This unit indicates mass multiplied by velocity.
What happens to the velocity of an object if a net force is acting on it?
The velocity will change
This is a direct application of Newton’s second law.
If object A exerts a force on object B, what will object B do?
Object B will exert an equal and opposite force on object A
This exemplifies Newton’s third law.
