Distance and Displacement
_________ is the direction from the start point and length of a straight line from start to end points.
Displacement
Speed = ?
Speed = distance / time
How is velocity different from speed?
Velocity describes speed and direction.
Velocity is a vector quantity while speed is speed is scalar.
Acceleration is the change in ________ over _______.
Acceleration is the change in velocity over time.
In order to describe motion accurately and completely, a _________ is necessary.
A)Direction
B) Frame of reference
C) Speed
D) position
B) Frame of reference
John walks 5 km North to the store, then walks back home 5 km South.
1) What was John's Distance?
2) What was John's Displacement?
1) Distance = 10 km
2) Displacement = 0 km
what are the SI units for speed?
m/s (meters per second)
How is it possible for 2 cars to be traveling the same speed but have different velocities?
They are moving in different directions
What does it mean if the acceleration of an object is negative?
the object is slowing down
What are the SI units for acceleration?
m/s2
Steve started home and walked 3 m east to the store, then another 5 m east to the park. When he got to the park he realized he lost his wallet and walked back to the store to look for it.
What was Steve's total distance traveled?
11 m
_____________ speed measures speed at a specific point.
Ex: Speedometer in a car
Instantaneous Speed
5 m/s east
When will an object that is moving have an acceleration equal to 0.
when their is no change in speed
What does the slope represent on a distance-time graph?
speed
Steve started home and walked 3 m east to the store, then another 5 m east to the park. When he got to the park he realized he lost his wallet and walked back to the store to look for it.
What was Steve's displacement?
3 m East
Sarah walked 100 meters in 25 seconds, realized she was running late, and sprinted 60 meters in 15 seconds. What was Sarah's average speed.
160 m / 40 s = 4 m/s
A boat is sailing 25 m/s north and the current is moving 8 m/s south. What is the boat's resultant velocity?
17 m/s North
A person on a bicycle is riding 15 m/s and two seconds later is going 20 m/s. What is the acceleration of the bicycle?
2.5 m/s2
What does a flat, horizontal line represent on a distance-time graph?
object is at rest
A car drove 9 miles East, turned, then traveled another 12 miles North.
What was the car's displacement?
a2 + b2 = c2
92 + 122 = c2
81+ 144 = c2
225 = c2
square root(225) = 15 miles Northeast
How long will it take a person to sprint 400 m if they run 2.5 m/s?
t=160 s
A cyclist rode their bike 3 m/s North, turned and rode west 4 m/s. What was the cyclist's resultant velocity?
5 m/s NW
A car is moving 75 m/s when all of a sudden it slams on brakes to avoid an accident. 15 seconds later it comes to a complete stop. Calculate acceleration.
-5 m/s2
Which frame of reference would be best to use when describing the motion of a moving car you are riding in?
A sign on the side of the road
Car in the lane next to you
A person sitting next to you in the car
1) A sign on the side of the road