Linear Momentum
Linear Momentum (p)
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Product of mass and velocity
Equation
p = mv
Vector quantity with direction the same
as v
Unit kg-m/s
Relationship with Inertia
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More momentum something has, the
harder it is to change its inertia
Greater effect it will have if in an impact
or collision
A force is required to change an
object’s momentum (increase it,
decrease it, or change it’s direction)
Newton’s 2nd Law
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Rate of change of momentum of a body
is equal to the net force applied to it more force,faster momentum changed
F = ma
a = Δv/t
F = m(v2 – v1) / t
F = p 2 – p1 / t
F = Δp / t
Example 1
For a top player, a tennis ball may leave
the racket on the serve with a speed of
55 m/s. If the ball has a mass of
0.060kg and is in contact with the
racket for 4 ms, what is the force on
the ball?
Example 2
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Water leaves a hose at a rate of 1.5kg/s
with a speed of 20m/s and is aimed at
the side of a car, which stops it. What
force is exerted by the water on the
car?
Example 3
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If the water splashes back from the car
at 15m/s, what is the force on the car?