Momentum Flashcards
(123 cards)
Define inertial mass.
A measure of a body’s tendency to resist a change in momentum.
How does Newton’s 2nd law relate to inertial mass?
F ∝ a the constant of proportionality is the inertial mass.
Define weight.
The force with which the earth pulls the body to the earth’s centre.
Why does weight vary from place to place?
Because the ‘g’ in F=mg varies from place to place.
What is the relationship between mass and weight?
Weight is the force of gravity on a mass (W=mg) they are proportional but not the same.
Are mass and weight the same?
No mass is the quantity of matter and weight is the force of gravity on that matter.
What is the effect of a net force on an object’s momentum?
It causes the object’s momentum to change.
What is the relationship between impulse and change in momentum?
Impulse is equal to the change in momentum.
In a closed system what happens to the total momentum during a collision?
The total momentum before the collision equals the total momentum after the collision.
What is the condition for the conservation of momentum?
No net external force acts on the system.
Why does a gun recoil when firing a bullet?
To conserve the total momentum of the system (gun + bullet).
How does the momentum of the bullet compare to the momentum of the recoiling gun?
They are equal in magnitude but opposite in direction.
In an elastic collision what happens to the total kinetic energy of the system?
It remains constant.
In an inelastic collision what happens to the total kinetic energy of the system?
It decreases.
Besides momentum what else is conserved in a perfectly elastic collision?
Kinetic energy.
In a perfectly inelastic collision what happens to the colliding objects?
They stick together and move as one.
In which type of collision is kinetic energy converted into other forms of energy?
Inelastic collision.
Give everyday examples that approximate elastic collisions.
Billiard balls colliding.
Give everyday examples of inelastic collisions.
A car crash.
Explain how the propulsion of a jet plane or rocket works.
By expelling gases at high velocity in one direction the plane/rocket gains momentum in the opposite direction.
Why is it possible to walk?
When you push against the ground the ground pushes you forward with an equal and opposite force.
What is the action-reaction pair in walking?
Your foot pushing on the ground (action) and the ground pushing on your foot (reaction).
What is the significance of Newton’s 2nd law in terms of momentum?
Force is equal to the rate of change of momentum (F = Δp/Δt).
How does Newton’s 2nd law relate force impulse and momentum?
Force multiplied by the time interval equals the change in momentum (FΔt = Δp = Impulse).
