So for every second the wind starts gusting, the boat is going 4 m/s faster.
So for every second the wind starts gusting, the boat is going 4 m/s slow, OR is going 4 m/s faster in the opposite direction.
Displacement Graph: AB: Got to Clackamas and realized we'd forgotten Grace. BC: Went back home to pick her up CD: Went to school DF: Stayed at school for the day Speed Graph: AB: accelerated BC: slowed to a stop CD: accelerated (maybe got on freeway) DF: traveled at a constant speed
At 30 seconds, car's speed is 20 m/s. Acceleration is 1 m/s/s from 0 to 20 seconds. Deceleration is 1 m/s/s (or -1m/s/s acceleration). Line is curved because acceleration is not constant (slope of line changes throughout).
750 m/s = 900 km/hr = 559 miles per hour kg m/s = SI unit for momentum Practical application: it will take a lot more force (energy) to slow or stop a cargo plane than it would a fly because of the difference in mass.
Transcript
1.
Changes in Speed & Direction Acceleration & Momentum
A train is traveling at 120 km/hr down a straight track. A runaway train is 700 km away on a collision course, going 230 km/hr. What is their relative velocity?
230 km/h + 120 km/h = 350 km/h
relative velocity = 350 km/h towards each other
How long do they have to fix this problem before the trains collide?
m/s 2 = change in velocity per second = m/s per second
Example: it takes my car 10 seconds to get up to 20 m/s North
Units of Acceleration acceleration = = m/s 2 20 m/s 2 m/s 2 North = 10 s 20 m/s 10 s = x = (change in velocity) 10 second acceleration 20 m s 0 m s 20 m s 1 10 s
Momentum gives us a measure of an object's inertia (its tendency to keep moving).
momentum = mass x velocity or p=m • v
Example: if a fly and a loaded cargo plane were both flying due East at 750 m/s, what would the momentum of each be? 10 mg x 750 m/s = 7,500 mg • m/s East .00001 kg x 750 m/s = .0075 kg •m/s East 330,000 kg x 750 m/s = 247,500,000 kg•m/s East mass = 10 mg mass = 330,000 kg
Which will hit the windshield of the oncoming car that appears out of nowhere with greater force?
Example: two flies, both with a mass of 10 grams, are racing Northwest to reach the garbage dump. What would the momentum of each be if Wolfie was going 10 m/s and Nannerl was flying 13 m/s? 10 mg x 10 m/s = 100 mg • m/s NW 10 mg x 13 m/s = 130 mg•m/s NW Wolfie Nannerl mass = 10 mg mass = 10 mg
When two object collide, momentum can be transferred.
No momentum is created or lost in the process.
Law of Conservation of Momentum:
if no other forces act on a set of objects, their total momentum remains the same after they interact
As the first ball is pulled back and released, it falls and collides with the next ball, transferring its momentum. This happens all down the line until the ball at the ends swings up and returns to again transfer that momentum back again through the balls.
Other examples: billiards (pool), air hockey, pedestrian hit by car
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