1. Unit 03 “Horizontal Motion”
Problem Solving

2. Problem Solving Steps 1st List Variables & Assign Values
2nd Choose Equation
3rd Plug In
4th Solve (Simply and/or Rearrange)
5th Box Answer

3. 1.
Edelin started to drive her car with an initial velocity of 10m/s. If she drives for 5 seconds with an acceleration of 4m/s2, what is her final velocity?
Vi =
Δt =
a =
Vf =
1st List Variables and Assign Values
Vf = Vi + aΔt
2nd Choose Equation
3rd Plug In
4th Solve (Simply, Rearrange)
5th Box Answer

4. Vf = Vi + aΔt Vf = Vi + a Δt Vf = 10m/s+ (4m/s2)(5s) 20m/s1.
Edelin started to drive her car with an initial velocity of 10m/s. If she drives for 5 seconds with an acceleration of 4m/s2, what is her final velocity?
Vi =
Δt =
a =
Vf =
10m/s 5s
1st List Variables and Assign Values
4m/s2 ?
Vf = Vi + aΔt
2nd Choose Equation
Vf = Vi a Δt
10m/s
(4m/s2)
(5s)
3rd Plug In
Vf = 10m/s+ (4m/s2)(5s)
20m/s
4th Solve (Simply, Rearrange)
Vf = 10m/s + 20m/s
30m/s
Vf = 30m/s
5th Box Answer

5. 2. How far does a car travel if, starting with a velocity of 5m/s, it drives for 10 seconds while accelerating at 3m/s2?

6. 2. How far does a car travel if, starting with a velocity of 5m/s, it drives for 10 seconds while accelerating at 3m/s2?
Δx = ViΔt + ½aΔt2
Δx =
Vi =
Δt =
a = ?
5m/s
Δx = (5m/s)(10s) + ½(3m/s2)(10s)2
10s
3m/s2
Δx = (5m/s)(10s) + ½(3m/s2)(100s2)
Δx = (50m) + ½(300m)
Δx = 50m + 150m
Δx = 200m

7. 3. A rollercoaster starts from rest and accelerates at a rate of 4m/s2 for 200m. How long does it take to reach this point?

8. 200m = (0m/s)(Δt) + ½(4m/s2)(Δt)2
3. A rollercoaster starts from rest and accelerates at a rate of 4m/s2 for 200m. How long does it take to reach this point?
Δx = ViΔt + ½aΔt2
Vi = 0 m/s
200m = (0m/s)(Δt) + ½(4m/s2)(Δt)2
a = 3m/s2
200m = (0) + (2m/s2)(Δt)2
Δx = 200m
200m = (2m/s2)(Δt)2
Δt = ?
2m/s2
2m/s2 √ √
100s2 = (Δt)2
10s = Δt

9. Vf2 = Vi2 + 2aΔx (8m/s)2 = (5m/s)2 + 2a(450m)
4. If the rollercoaster car is moving at a speed of 5m/s and then accelerates to a final speed of 8m/s over a distance of 450m, what is the car’s acceleration?
Vf2 = Vi2 + 2aΔx
Vi =
Vf =
Δx =
a =
5m/s
8m/s
(8m/s)2 = (5m/s)2 + 2a(450m)
450m ?
64m2/s2 = 25m2/s m(a)
-25m2/s2
-25m2/s2
39m2/s2 = 900m(a)
900m
900m
0.0433m/s2 = a

10. Easy Practice Problems
Solve the following EASY problems on your white board in your small groups.
Delyla kicks a soccer ball from rest giving it an acceleration of 1.5m/s2 for 14s, how fast does it go in the end?
Issa slows his car from a velocity of 30m/s for 12s with an acceleration of -3m/s2, how far did he go?
Joan is pushing his brother on his bike when he asks him to go faster. If the bike changes speed from 4m/s to 8m/s in 10seconds, how far have the brothers traveled in this time?
What is the final velocity of a car driven by Mr. Hunt if it starts from rest and accelerates at a rate of 2m/s2 for 25m?
#1 Answer: 21m/s
#2 Answer: 144m
#3 Answer: 60m
#4 Answer: 10m/s

11. Medium Practice Problems
Solve the following Medium problems on your white board in your small groups.
Chanda bikes with a velocity of 12m/s and then accelerates at 3 m/s2 for 20m. What is her final velocity?
What is the acceleration of Michael’s car if he starts with a velocity of 40m/s and speeds up to a velocity of 70m/s for 3 seconds as he races around the Thurber’s Avenue curve on route 95?
Destiny pushes a soccer ball so it accelerates from a velocity of 8m/s to 2m/s. If it rolls for 2 seconds, what is the acceleration?
What is the initial velocity of a ball that Ms Bucci pushes to accelerate at 2m/s2 for 7 seconds and ends with a final velocity of 35m/s?
Tylor rides his bicycle with a velocity of 12m/s, if he accelerates at a rate of 3m/s2 and ends with a velocity of 38m/s, how long did it take?
#5 Answer: 16.2m/s
#6 Answer: 10m/s2
#7 Answer: -2m/s2
#8 Answer: 21m/s
#9 Answer: 8.67s

12. Vf = Vi + a∆t 70m/s= 40m/s + (a)(3s) 30m/s = (a)(3s) 10m/s2 = a
Medium Example
6. What is the acceleration of Micahel’s car if she starts with a velocity of 40m/s and speeds up to a velocity of 70m/s for 3 seconds as she races around the Thurber’s Ave curve of route 95?
Vf = Vi + a∆t
70m/s= 40m/s + (a)(3s)
30m/s = (a)(3s)
10m/s2 = a
Vi = 40m/s
Vf = 70m/s
Δt = 3s
a = ?