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