In Motion: A Physics Unit
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Transcript of In Motion: A Physics Unit
In Motion:A Physics Unit
I love physics, but I hate moving.
Rearranging equations:
• Used to find an unknown value.
• Goal is to get only the unknown alone on one side of the equation.
One rules for moving variables around:
“Moving a variable ACROSS the equal sign CHANGES the OPERATION.”
Move variables that are multiplied or divided:
“Moving ACROSS the equal sign CHANGES the OPERATION.”
=
V1 V2
T2
T1
4 = H 2
2 x 4 = H 8 = H
Move variables that are added or subtracted:
“Moving ACROSS the equal sign CHANGES the OPERATION.”
=
V1 d f + a - a- 24 = x
4 + 2 = x6 = x
=
2x P + T- T =
(a)(F) P (T)
y = x + bm
y – b = mx
y – b = mx
m = y – bx
= 8 4
4 = 8 A
A x 4 = 8
A = 2
Speed or Velocity
Speed is how fast an object moves.
Speed is scalar. It has a size but no direction.
The symbol for speed is
vThe units of speed can be km/h OR m/s or cm/min
Speed is calculated as the total distance travelled over the total time it took to travel
This is actually the average speed.
v = Δd t
distance
time interval
If you travel from Winnipeg to Flin Flon, a distance of 700 km in 7 hours, your speed is?
v = 100 km/h
v = Δdt v =
700 km7 h
How long did it take a person driving 50 km/h to go a distance of 300 km?
Δd = 300 km t = ?
v = 50 km/h
t = 300 km 50 km/h
t = 6 h
= Δd v
v = Δd t
t x v = Δd
t
1 h 60 min
1 min60 s
A skate boarder moves at a speed of 5 m/s, how far does he go in 1 hour?
Δd = ? t = 1 h v = 5 m/s
5 = Δd 3600
3600 x
Δ d = 18000 m
v =Δ d
t
Your units always have to match.
1 h x x = 3600 s
Velocity measures a change in position with time.
Velocity is a vector quantity.
(SPEED is total distance over time)
Velocity is calculated as displacement over time.
v = d t
If you travel from Winnipeg to The Pas, displacement of 420 km [south]. The trip takes 4.00 hours. Velocity is:
105 km/h[south] v = 420 km[south]
4.00 h
v = d t ∆d = 420 km [s]
∆t = 4.0 hr
v = ?
A car with a velocity of 20 m/s north, traveled for 60 seconds, what was the displacement?
∆d = ?∆t = 60 s
v = 20 m/s [N]
∆d = 1200 m [N]
∆d = 60 s x 20 m/s [N]
v = Δd t
t x v = Δd
If the stickman below takes 2 seconds to walk, calculate distance, displacement, speed, velocity:
11 cm
6 cmΔd = 11 + 6 + 11Δd = 28 cm
∆d = d2 - d1
∆d = 6 cm - 0 cm ∆d = 6 cm (down)
∆t = 2 s
11 cm
6 cm
Δd = 28 cm
∆d = 6 cm (down)
v = Δd t
v = d t
t = 2 s
v = 28 cm 2 s
v = 14 cm/s
v = 6 cm (down)
2 s
v = 3 cm/s (down)
d = d2 - d1
v = d t
v = Δd t
t = t2 - t1