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Newton’s 1st Law
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Scalars and Vectors
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Kinematic quantities: Position,
Displacement, Velocity
A spaceship far from all other objects uses its rockets to attain a speed
of 104 m/s. The crew then shuts off the engine. According to Newton’s
first law, which of the following statements about the motion of the
spaceship after the engine is shut off are correct?
1 The spaceship will move in a straight line.
2 The spaceship will travel on a curved path.
3 The spaceship will enter a circular orbit.
4 The speed of the spaceship will not change.
5 The spaceship will gradually slow down.
6 The spaceship will come to an immediate
stop.
Vectors and Scalars
Physical quantities come in two types
Scalars
and
Vectors
Vector Addition
Add the vectors
⃗
A
and
⃗
B
⃗
A
⃗
B
Vector Addition
⃗
A
⃗ +B
⃗
A
⃗
A
⃗ +B
⃗
A
1. My solution looks like one of these
⃗
B
⃗
B
⃗ +B
⃗
A
⃗
B
⃗
B
⃗
A
⃗
A
2. No, this is it!
⃗ +B
⃗
A
3. Both wrong, this is it
Vector Subtraction
Subtract vectors
⃗
A
and
⃗
B
⃗
A
⃗ B
⃗
A−
⃗
B
Vector Subtraction
⃗ +(− B)
⃗
A
−⃗
B
⃗
A
⃗
A
1. My Solution looks like one of these
⃗ B
⃗
A−
⃗
B
−⃗
B
⃗ +(− B)
⃗
A
⃗
B
⃗
A
⃗
A
2. No, this is it!
⃗ B
⃗
A−
3. Both wrong, this is it
Course to Athens 80 degrees
Wind 220 @ 30 kts
Airplane 100 kts moving through the air
In which heading must I to steer the airplane to fly in a straight line to Athens?
wind from 220° @ 30 kts
Course to Athens 80 degrees
Wind 220 @ 30 kts
Airplane 100 kts moving through the air
In which heading must I to steer the airplane to fly in a straight line to Athens?
v overground
⃗
v plane
⃗
v wind
⃗
Calculate the Displacement Vector
from
⃗i
P
to
P⃗f
⃗i =⟨ 1m ,1m , 4 m⟩
P
P⃗f =⟨ 4 m ,3 m , 0 m⟩
Calculate the Displacement Vector
1.
Δ⃗
P =⟨ 3 m , 2m ,−4 m⟩
2.
Δ⃗
P =⟨−3 m ,−2 m , 4 m⟩
3.
Aehh, shoot
Calculate the Average Speed
Δ⃗
P =⟨ 3 m , 2m ,−4 m⟩
t i=4.6 s
t f =6.6 s
Calculate the Average Speed
Δ⃗
P =⟨ 3 m , 2m ,−4 m⟩
1.
2.7 m/s
2.
4.5 m/s
3.
2 m/s
4.
1.4 m/s
5.
Is it weekend yet?
t i=4.6 s
t f =6.6 s