Momentum

Try coming up with your own idea of what you Try coming up with your own idea of what you think momentum is. Write this down below think momentum is. Write this down below the bold Momentum title and label it “pre-the bold Momentum title and label it “pre-

definition.”definition.”

Let's consider a few examples. Look at the Let's consider a few examples. Look at the one in your notes. How can this be true?one in your notes. How can this be true?

Here's another situation to boggle your mind. Here's another situation to boggle your mind. Would it be possible for a bike rider to collide Would it be possible for a bike rider to collide with a truck and have the truck bounce back?with a truck and have the truck bounce back?

Questions of the day =) Why do we fly forward in a car when someone

slams on the breaks?

How is it that a piece of straw can pierce through a wooden stake during a tornado?

Have you ever run so fast that you can’t stop yourself and you trip forward? Why might that be?

Why does it take trains nearly a mile to come to a complete stop?

So let's define momentum together...

The force of motion created by the product of the mass of an object and its

velocity. It can determine how difficult it is to stop an object in motion.

Momentum = mass (m) x velocity (v)

(p = m x v)

How bout the units?Mass is measured in g, kg, etc.

Velocity is measured in m/s (could also be km/hr)

So our end units cannot be simplified any more than kg●m/s

What is the formula for momentum?

If it takes a car traveling 25mi/hr 20ft to stop, why does it take the same car 40ft to stop

when it is traveling 50mi/hr?

Based on our equation, the greater velocity an object has, the more momentum it will have. Due to a

higher momentum, it will take the car longer to stop when traveling at a

faster speed.

Define the law of Conservation of Momentum:

The total The total momentum of any momentum of any group of objects group of objects remains the same, remains the same, unless acted on by unless acted on by an outside force.an outside force.

(Momentum is (Momentum is transferred from one transferred from one object to the next object to the next during a collision but during a collision but is not lost)is not lost)

Momentum Problems...A skier having a mass of 60kg travels down

the mountain at 20m/s. What is the momentum of the skier?

Setup:

p = m x vMomentum = 60kg x 20m/sMomentum = 1200.0kg●m/s

Next one...

If a frog has a mass of 0.9kg, with what momentum will it hit the water if it jumps at a

velocity of 12m/s?

Setup:

p = m x vMomentum = 0.9kg x 12m/sMomentum = 10.8kg●m/s

If the car below (1500kg) is traveling at 30m/s and collides head-on with the truck (2500kg) traveling at 15m/s, which vehicle will push the other backwards? How do you know?

Well, we should probably set up the problem before we make

assumptions...

Car's Momentum = m x vCar's Momentum = 1500kg x 30m/sCar's Momentum = 45,000.0kg●m/s

Truck's Momentum = m x vTruck's Momentum = 2500kg x 15m/sTruck's Momentum = 37,500.0kg●m/s