1. How to Solve Physics Problems

2. 7 Step Guide to Problem Solving
Put your calculator down!
Step #2
Read the problem thoroughly.
Key into words like: constant, from rest, accelerating, coming to a stop

3. 7 Step Guide to Problem Solving
A. Identify
Known Variables, fill in the chart
Variable
Value
Vi (Initial Velocity)
Vf (Final Velocity)
a (acceleration)
∆X (Change in Distance)
∆t (time interval) ∆D

4. 7 Step Guide to Problem Solving
B. Determine what you are solving for?
Variable that you are being asked to find.
C. Draw a sketch of the scenario.

5. 7 Step Guide to Problem Solving
Step #4: Pick an Equation

6. 7 Step Guide to Problem Solving
Step #5: Rearrange the equation to solve for desired variable
EX: We selected this equation:
Rearrange to solve for a.

7. 7 Step Guide to Problem Solving
Step #6: Solve
Start plugging in values for known variables.
Step #7: Check your answer
1. Does the answer make sense?
2. Are the units correct?

8. Example Problems
A car starts from rest and accelerates to a velocity of 25.0 m/s over a distance of meters. How long did it take the car to reach 25.0 m/s?
Step #2: Key terms

9. Example Problems
A car starts from rest and accelerates to a velocity of 25.0 m/s over a distance of meters. How long did it take the car to reach 25.0 m/s?
Step #3: Table
Solving for t
Variable
Value Vi Vf a ∆X ∆t
25 m/s ?
100 m ?

10. Example Problems
A car starts from rest and accelerates to a velocity of 25.0 m/s over a distance of meters. How long did it take the car to reach 25.0 m/s?
Step #4: Select equation
Variable
Value Vi Vf
25.0 m/s a ? ∆X
100.0 m ∆t

11. Example Problems
A car starts from rest and accelerates to a velocity of 25.0 m/s over a distance of meters. How long did it take the car to reach 25.0 m/s?
Step #5: Rearrange Equation

12. Example Problems
A car starts from rest and accelerates to a velocity of 25.0 m/s over a distance of meters. How long did it take the car to reach 25.0 m/s?
Step #6: Solve

13. Example Problems
A car starts from rest and accelerates to a velocity of 25.0 m/s over a distance of meters. How long did it take the car to reach 25.0 m/s?
Step #7: Check
1. Is the answer reasonable?
2. Are the units correct?

14. Example Problems
A ball is thrown straight up in the air with an initial velocity of 10.0 m/s and then caught at the same height 2.04 seconds later.
What is the acceleration of the ball after it leaves the throwers hand?
How high will the ball go up before falling back down?

15. Example Problems
A ball is thrown straight up in the air with an initial velocity of 10.0 m/s and then caught at the same height 2.04 seconds later.
Step #2: Key Terms
Step #3: Table
Variable
Value Vi Vf a ∆X ∆t
0 m/s
-10.0 m/s ? ?
WHAT? Why 1.02 sec?
1.02 s

16. Example Problems
A ball is thrown straight up in the air with an initial velocity of 10.0 m/s and then caught at the same height 2.04 seconds later.
What is the acceleration of the ball after it leaves the throwers hand?
Step #4: Select an Equation
Step #5: No need
to rearrange

17. Example Problems Step #6: Solve
Variable
Value Vi
0 m/s Vf
-10.0 m/s a ∆X ? ∆t
1.02 s
For problems that occur in the air, the acceleration is due to gravity and is always m/s
-9.81 m/s2
What is the acceleration of the ball after it leaves the throwers hand?

18. Example Problems
b) How high will the ball go up before falling back down?
Ans: m from the math, correct answer is 5.10 m based on the question