Momentum and Impulse Flashcards
Momentum
p = mv
Momentum
sum of p = p1 + p2 …
Measuring a chance in momentum
When an object undergoes either a change in its velocity, its momentum changes.
delta p = mv - mu
Force Time Graph
During an interaction, the extent of the force acting can be best understood by analysing a force -time graph. Not only will this allow the peak force acting on an object, but it can also be used to determine the overall impulse the object experienced.
The area under the curve represents the impulse.
Conserving momentum
The law of conservation of momentum states that for two objects colliding in an isolated system, the total momentum before and after the collision is equal.
m1u1 + m2u2 = m1v1 + m2v2
Analysing the collision between two objects
When two objects collide, Newton’s third law applies. The force exchanged between two forces is equal in magnitude, but opposite in direction. As the collision occurs for the same timeframe for each of the objects, their impulses will be equal in magnitude.
F1 on 2 = -F2 on 1
J1 = -J2
Defining a Collision
A collision is an interaction between two objects where they apply a force to each other. They happen over very small time intervals. The time frame is so small that there is no point in considering the acceleration, so its just th eimpulse.
During a collision
- Momentum and energy are transferred between two or more objects.
- Total momentum is always conserved.
- Some kinetic energy may be lost, or transformed e.g. gpe, sound , heat, light
Collisions in one dimension
Elastic collision is where KE is conserved. Inelastic collision KE is not conserved. Elastic collisions is when two objects bounce back. In inelastic, the kinetic energy of mass 1 is dissolved and mass 2 go back.
Difference between elastic and inelastic collisions
Elastic collisions tend to see objects bouncing off each other, whereas inelastic collisions are more likely to stick together. Elastic collisions conserve kinetic energy, whereas inelastic ones transform kinetic energy into other forms of energy.
Momentum is conserved between both collisions.
Kinetic energy is conserved in elastic collisions.
Other energy forms in inelastic.
Explosions
When an explosion occurs, one object is broken into two parts. Mathematically, explosions can be thought of as a type of collision. Momentum is conserved.
Explosions and applying the law of conservation of momentum
m1u1 = m2v2 + m3v3…
When masses combine
When two masses combine to form one mass the formula becomes:
m1u+m2u2+ = m3v3