IMPULSE AND MOMENTUM
Momentum
Momentum is a measurement of mass in motion. Any object that is moving has momentum. In physics,
momentum of an object is equal to the mass times the velocity.
momentum = mass * velocity
Momentum is usually abbreviated using the letter "p" making the equation look like:
p = m * v
where p is the momentum, m is the mass, and v is the velocity.
โpโ came from the Latin word "petere" which means "go towards".
Based from the equation, both the velocity of the object and the mass have an equal impact on the amount of
momentum. You have more momentum when you are running than when you are walking. While, if a car and
bicycle are traveling down the street at the same velocity, the car will have more momentum.
Momentum is typically measured in kilograms times meters per second (kg m/s) or newton-second (N s).
Because velocity is a vector, momentum is also a vector. This means that in addition to the magnitude of
momentum (which is given by p = m * v), momentum also has a direction. The direction of momentum is shown
by an arrow or vector.
SAMPLE PROBLEMS:
1. A 50 kilogram boy runs as fast as 4m/s to the north. What is his momentum?
given: m= 50 kg
v= 4 m/s, north
unknown: p
formula: p=m*v
solution: p=(50kg)* (4m/s, north)
answer: p= 200 kg m/s, north
2. The momentum of a 100-kilogram cart is 2000 kg m/s, south. How fast is the cart going?
given: m= 100 kg
p= 2000 ๐๐ ๐/๐ , south
unknown: v
formula: ๐ฃ = ๐/๐
solution: ๐ฃ = 2000๐๐๐๐ ,๐ ๐๐ข๐กโ/100 ๐๐
answer: v = 20 m/s, south
Impulse
Impulse is a term that quantifies the overall effect of force acting over time. It is conventionally given the symbol I,
and expressed in Newton-seconds N.s). For a constant force, I = F โ
ฮt.
Impulse concepts are merely results of Newton's second law- law of acceleration. Newton's second law
(Fnet = m โข a) stated that the acceleration of an object is directly proportional to the net force acting upon the
object and inversely proportional to the mass of the object. When combined with the definition of acceleration
(a = change in velocity / time), the following equalities result.
F โข t = m โข ฮv
Impulse = Change in momentum
Example:
Tiger Woods hits a 0.02 kg golf ball, giving it a speed of 25 m/s. What impulse does he impart to the ball?
Given: m = 0.02 kg
