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Video Instruction

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C. Solving Word Problems ex) A car accelerates uniformly from rest at a rate of +10 m/s2. How far will the car travel in 4 seconds?

• Step 1 - Read and underline all the important information

ex) A car accelerates uniformly from rest at a rate of +10 m/s2. How far will the car travel in 4 seconds?

Step 2 - Turn all your information into letters

Vi = 0 (starts from rest)

a = +10 m/s2

t = 4 seconds

d = ?

Step 3 - Substitute and Solve Equation: Δd = Vit + (1/2)aΔt2

= 0 m/s(4 sec)+1/2(10 m/s2)(4s)2

Δd = 0 + 5(16)

Δd = 80 m D. Deriving the 2nd displacement equation:

`Vf2 = Vi2 + 2aΔd`
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`d = VΔt`
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 Δd = (Vf + Vi) Δt 2
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``` since Vf = Vi + aΔt
then Δt = (Vf -Vi)/a```
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 Δd = (Vf + Vi) (Vf - Vi) 2 a
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 Δd = (Vf2 - Vi2) 2a
`Cross Multiply`
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 2aΔd = Vf2 - Vi2
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 Vf2 =(Vi2 + 2aΔd) Ex) A car with an initial velocity of +6 m/s accelerates at a rate 2 m/s2. Find the cars final velocity after it travels 7 m from its initial position "Step 1 - Read and underline all the  important information "

Ex) A car with an initial velocity of +6 m/s accelerates at a rate 2 m/s2. Find the cars final velocity after it travels 7 m from its initial position "Step 2 - Turn all your information  into letters"

Vi = 6 m/s
a = 2 m/s2
Vf = ?
d = 7 meters "Step 3 - Substitute and Solve" Vf2 = Vi2 + 2aΔd

Vf2  = (6 m/s)2 + 2(2 m/s2)(7 m)

Vf2  = 36 + 4(7)

Vf2 = 64

Vf = 8 m/s  Displacement Plots  