9.3 Conservation of momentum Flashcards
What is Newton’s third law of motion
When two objects interact, they exert equal and opposite forces on each other
Real world example of Newton’s third law of motion
The Earth exerts a force due to gravity on an object which exerts an equal and opposite force on the Earth
A jet engine exerts a force on hot gas in the engine to expel the gas - the gas being expelled exerts an equal and opposite force on the engine
Key thing to know about the forces in Newton’s third law of motion
They must be of the same type and acting on different objects for them to be considered a force pair
What changes when an object is acted on by a resultant force
The object’s momentym changes
If there is no change of momentum, there can be no resultant force
What is the principle of conservation of momentum
It states that for a system of interacting objects, the total momentum remains constant, provided no external resultant force acts on the system
What is the total final momentum equal to
The total initial momentum
Experiment arrangement to test conservation of momentum
Set up two clamp stands 30cm apart
Connect light detector to one and source to other
Connect detector to computer and source to battery
Get a trolley with a piece of card on it
Computer records and displays the velocity of trolley throughout time
Equation to show the conservation of momentum from the trolley experiment
(mB+mA)V=mAuA
Where velocity of trolley A = uA
