1. Using Formulas

2. Steps for Solving Formula Problems
Choose the correct formula (if it not given to you in the problem)
Identify what to substitute for each variable
Substitute
Solve the resulting equation

3. Click on the yellow star above that you think is the correct answer.
The kinetic energy of an object can be found with the formula , where is the energy in joules, m is the mass in kilograms, and v is the velocity in meters per second. A dog with a mass of 5 kilograms has 250 joules of kinetic energy when moving at what speed?
Great
Job!
In the above problem, what would you substitute for m?
A. m=250
Remember that m is the mass. What is the mass of the dog?
Working!
B. m=5
C. m=50
Remember that m is the mass. What is the mass of the dog?
D. Nothing, m is the variable that needs to be solved for.
Click on the yellow star above that you think is the correct answer.

4. Click on the yellow star above that you think is the correct answer.
The kinetic energy of an object can be found with the formula , where is the energy in joules, m is the mass in kilograms, and v is the velocity in meters per second. A dog with a mass of 5 kilograms has 250 joules of kinetic energy when moving at what speed?
Fantastic!
In the above problem, what would you substitute for v?
Remember that v is the velocity. Do we know the velocity of the dog?
A. v=250
Working!
B. v=5
Do we know the velocity of the dog?
C. v=50
Remember that v is the velocity.
D. nothing, v is the variable that needs to be solved for
Click on the yellow star above that you think is the correct answer.

5. Click on the yellow star above that you think is the correct answer.
The kinetic energy of an object can be found with the formula , where is the energy in joules, m is the mass in kilograms, and v is the velocity in meters per second. A dog with a mass of 5 kilograms has 250 joules of kinetic energy when moving at what speed?
You
Rock!
In the above problem, what would you substitute for ?
A. =250
Remember that is the energy in joules.
What is the energy in joules of the dog?
Working!
B. =5
Remember that is the energy in joules.
What is the energy in joules of the dog?
C. =50
D. nothing, is the variable that needs to be solved for
Remember that is the energy in joules. What is the energy in joules of the dog?
Click on the yellow star above that you think is the correct answer.

6. The Three Questions What is the mass of the dog?
Do we know the velocity of the dog?
What is the energy in joules of the dog?
(Remember that v is the velocity.)
(Remember that is the energy in joules.)

7. Click on the yellow star above that you think is the correct answer.
The kinetic energy of an object can be found with the formula , where is the energy in joules, m is the mass in kilograms, and v is the velocity in meters per second. A dog with a mass of 5 kilograms has 250 joules of kinetic energy when moving at what speed?
Smarty 
Which is the equation you would need to solve after substituting?
A. 250= ½ m(5)2
Refer back to the last 3 questions to see
what can be substituted for each variable
Working!
B. = ½(5)(250)2
C. 250= ½(5)v2
Refer back to the last 3 questions to see
what can be substituted for each variable
D. 5= ½ (250)v2
Refer back to the last 3 questions to see
what can be substituted for each variable
Click on the yellow star above that you think is the correct answer.

8. Click on the yellow star above that you think is the correct answer.
The kinetic energy of an object can be found with the formula , where is the energy in joules, m is the mass in kilograms, and v is the velocity in meters per second. A dog with a mass of 5 kilograms has 250 joules of kinetic energy when moving at what speed?
Way to
Go!
Which is the solution to this problem?
A. 5 meters per second
Take the equation from the last slide and solve for v.
Working!
B. 10 meters per second
Take the equation from the last
slide and solve for v.
C. 50 meters per second
D. 100 meters per second
Remember if you have v2=100,
you need to take the square root of both sides to solve for v.
Click on the yellow star above that you think is the correct answer.

9. Here is the work for this problem so you can check your work.
The kinetic energy of an object can be found with the formula , where is the energy in joules, m is the mass in kilograms, and v is the velocity in meters per second. A dog with a mass of 5 kilograms has 250 joules of kinetic energy when moving at what speed?
Here is the work for this problem so you can check your work.
250= ½(5)v2
250=2.5v2 multiply ½ times 5
100=v2 Divide both sides by 2.5
10=v  Take the square root of both sides

10. Click on the yellow star above that you think is the correct answer.
The formula describes the relationship between the focal length of a camera lens (f), the distance an object is from the lens (d0 ), and the distance the image of the object is from the lens (di ). What is the focal length, in centimeters (cm), of a lens when an object is placed 3 cm from the lens and the image is 6 cm from the lens?
Oooh,
Ahhh!
  In the above problem, what would you substitute for f?
Working!
A. f=6
Remember that f is the focal length of the lens. Are we given this value?
B. f=3
Remember that f is the focal length of the lens. Are we given this value?
C. f=9
Remember that f is the focal length of the lens. Are we given this value?
D. nothing, f is the variable that needs solved
Click on the yellow star above that you think is the correct answer.

11. Click on the yellow star above that you think is the correct answer.
The formula describes the relationship between the focal length of a camera lens (f), the distance an object is from the lens (d0 ), and the distance the image of the object is from the lens (di ). What is the focal length, in centimeters (cm), of a lens when an object is placed 3 cm from the lens and the image is 6 cm from the lens?
Great
Mind!
  In the above problem, what would you substitute for do?
Working!
A. d0=6
Remember that d0 is the distance the object is from the lens.
B. d0=3
C. d0=9
Remember that d0 is the distance the object is from the lens.
D. nothing, d0 is the variable that needs solved for.
Click on the yellow star above that you think is the correct answer.

12. Click on the yellow star above that you think is the correct answer.
The formula describes the relationship between the focal length of a camera lens (f), the distance an object is from the lens (d0 ), and the distance the image of the object is from the lens (di ). What is the focal length, in centimeters (cm), of a lens when an object is placed 3 cm from the lens and the image is 6 cm from the lens?
Wow!
In the above problem, what would you substitute for di?
Working!
A. di=6
Remember that di is the distance the Image of the
object is from the lens?
B. di=3
Remember that di is the distance the Image of the
object is from the lens?
C. di=9
D. nothing, di is the variable that needs solved for.
Click on the yellow star above that you think is the correct answer.

13. Click on the yellow star above that you think is the correct answer.
The formula describes the relationship between the focal length of a camera lens (f), the distance an object is from the lens (d0 ), and the distance the image of the object is from the lens (di ). What is the focal length, in centimeters (cm), of a lens when an object is placed 3 cm from the lens and the image is 6 cm from the lens?
Impressive!
Which is the equation you would need to solve after substituting? A.
Refer back to the last 3 questions to see
what can be substituted for each variable. B.
Refer back to the last 3 questions to see
what can be substituted for each variable. C.
Refer back to the last 3 questions to see
what can be substituted for each variable. D.
Click on the yellow star above that you think is the correct answer.

14. Click on the yellow star above that you think is the correct answer.
The formula describes the relationship between the focal length of a camera lens (f), the distance an object is from the lens (d0 ), and the distance the image of the object is from the lens (di ). What is the focal length, in centimeters (cm), of a lens when an object is placed 3 cm from the lens and the image is 6 cm from the lens?
Good
Answer!
Which is the solution to this problem?
 A.  ½ cm
Take the equation from the last slide, find a common denominator, add and simplify. Then
finish solving from there.
B. 1/9 cm
Take the equation from the last slide, find a common denominator, add and simplify. Then finish solving from there.
C. 2 cm
Take the equation from the last slide, find a common denominator, add and simplify. Then finish solving from there.
D. 9 cm
Click on the yellow star above that you think is the correct answer.

15. Here are the steps for this problem so you can check yourself.
The formula describes the relationship between the focal length of a camera lens (f), the distance an object is from the lens (d0 ), and the distance the image of the object is from the lens (di ). What is the focal length, in centimeters (cm), of a lens when an object is placed 3 cm from the lens and the image is 6 cm from the lens?
Here are the steps for this problem so you can
check yourself.
Rewrite the fractions with a common denominator.
Add the fractions and simplify.
Take the reciprocal of both sides.