Quantity / Formula / Units
Speed / / m/s
Velocity / / m/s With Direction
Acceleration / / m/s2
Force / / N or kg ∙ m/s2
Weight / / N or kg ∙ m/s2
Work / / J or N ∙ m
Power / / w

Metric Conversion

Remember: King Henry Doesn’t Usually Drink Chocolate Milk

Units – My Large giraffe (Meters, Liters, grams)

Examples:

Soda cans contain 355ml of soda. How many Liters is this?

A former Hillcrest graduate has become a chocolatier and must prepare chocolate candies for a wedding. She has 300 kg of chocolate how many grams is this?

The Hillcrest graduate also needs flower to complete her confection. She has 50 hectograms but needs to know how much she need in milligrams.

Dimensional Analysis

  1. List what you know.
  2. List what you need to know.
  3. Set up problem.
  4. Put the value you WANT on the top line of the last fraction.
  5. Cancel out all unwanted units.
  6. Solve.

Examples(A conversion chart will be provided on the test)

Ms. Miles has student loans. If it took 50 years to pay off those loans how long in months would that take?

  1. What you know:
    50 years
    1 year = 12 months
  2. What you need to know:
    Months = ?
  3. Set up problem:

  4. Put the value you want on the top line of the last fraction.
  5. Cancel out units.
  1. Solve
    50 x 12 months = 600 months

Usain Bolt runs on a track every day. The track is 1000 feet. How many meters is this?

  1. What you know:
    1000 ft
    1 mile = 5280ft
    1 km = 0.621 mi
    1 km = 1000 m
  2. What you need to know:
    meters = ?
  3. Set up problem:

  4. Put the value you want on the top line of the last fraction.
  5. Cancel out units.
  1. Solve

How to solve ALL physics problems:

  1. Write which formula you will need.
  2. List the variables you do have and figure out what is missing.
  3. (If needed) rearrange the formula to solve for missing variable.
  4. Plug in values into their correct locations.
  5. Solve.

Speed S = speedd = distancet = time

A vehicle travels 60 m in 40 s. What was the vehicle’s speed?

  1. Write the formula needed.
  1. List the variables you have:
    d = 60 m
    t = 40 s
    S = ?
  2. No rearrangement needed for this problem.
  3. Plug in values into their correct locations.
  4. Solve.
    S = 1.5 m/s

A plane has a speed of 34 km/s over a time of 50s. How far did the vehicle travel?

  1. Write the formula needed.
  1. List the variables you have:
    d = ?
    t = 50s
    S = 34 km/s
  2. Rearrange to solve for missing variable.
  3. Plug in values into their correct locations.
  4. Solve.
    d = 1700km

A plane travels at a speed of 78 m/s over a distance of 8000 m. How long did this take in hours?

  1. Write the formula needed.
  1. List the variables you have:
    d = 8000m
    t = ?
    S = 78 m/s
  2. Rearrange to solve for missing variable.
  3. Plug in values into their correct locations.
  4. Solve. *Remember, this question asks for the value in hours.
    t = 102.56s

Velocity

A vehicle travels for 20m from rest in 56 seconds. What was its velocity?

  1. Write the formula needed.
  1. List the variables you have:
    Xf = 20m
    Xi = 0m
    tf = 56s
    ti = 0s
    V = ?
  2. No rearrangement necessary for this problem.
  3. Plug in values into their correct locations
  1. Solve.
    V= 0.36 m/s

During a race a runner’s velocity was measured at 2.5s when she was at the 50m point and the time was stopped at the100m point.Her velocity was found to be 13m/s. What was her final time?

  1. Write the formula needed.
  1. List the variables you have:
    Xf = 100m
    Xi = 50m
    tf = ?
    ti = 2.5s
    V = 13 m/s
  2. Rearrange the problem to find the missing variable.
  3. Plug in values into their correct locations
  1. Solve.
    tf = 6.3s

The SR-71 Blackbird holds the world record for the fastest manned airplane with a velocity of 3529.6 km/h. How far would the Blackbird fly in 32,400s?

  1. Write the formula needed.
  1. List the variables you have:
    Xf = ?
    Xi = 0m
    tf = 32,400s
    ti = 0s
    V = 3529.6 km/h
  2. Rearrange the problem to find the missing variable.
  3. Plug in values into their correct locations
  1. Solve.
    Xf = 31, 766.4 km

Acceleration

To pass a car you speed up from 67 m/s to 89 m/s over 20s. What was your acceleration?

  1. Write the formula needed.
  1. List the variables you have:
    Vf = 89 m/s
    Vi = 67 m/s
    tf = 20s
    ti = 0s
    a = ?
  2. No rearrangement necessary.
  3. Plug in values into their correct location.
  1. Solve.
    a = 1.1 m/s2

A rocket accelerates into space at a rate of 769 m/s2 over a time period of 60s. What was its final velocity?

  1. Write the formula needed.
  1. List the variables you have:
    Vf = ?
    Vi = 0 m/s
    tf = 60s
    ti = 0s
    a = 769 m/s2
  2. Rearrange to find missing variable.
  3. Plug in values into their correct location.
  1. Solve.
    Vf = 46,140 m/s

An object was found to have an acceleration of 78 m/s2 with an initial velocity of 12 m/s and a final velocity of 34 m/s. What was the final time of the object’s movement?

  1. Write the formula needed.
  1. List the variables you have:
    Vf = 34 m/s
    Vi = 12 m/s
    tf = ?
    ti = 0s
    a = 78 m/s2
  2. Rearrange to find missing variable.
  3. Plug in values into their correct location.
  1. Solve.
    tf = 0.28 s

Force, weight, work, and power are all similar to the formula for speed. If you can calculate speed you can calculate the others.

Practice Problems – On a separate sheet of paper. Show all your work.

1) The weight of a flash drive is 3 grams. Convert the measurement to centigrams.

2) The distance between Cell Phone Company A and B is 87 m. Convert the measurement to cm.

3) 76.2 m of CL2 in-wall speaker cable was installed in an office for background music.

A.) Calculate that length in decameters.

B) Calculate that length in centimeters.

4) A wireless router supports a range of up to 4,572 cm indoors.

A) Calculate that length in meters.

B) Calculate that length in kilometers.

5) When storing and stacking laptop computers you need to take into account the mass of the object. A typical laptop computer has a mass of about 4 kg.

A) Calculate that mass in grams.

B) Calculate that mass in milligrams.

1 lb = 454 g 1 qt = 0.946 L 1g = 0.04oz

6) A sample of seawater contains 0.000245 g of sodium chloride per mL of solution. How much sodium chloride is contained in 50.0 mL of this solution?

7) Convert 3598 grams into pounds.

8) Convert 231 grams into ounces.

9) A beaker contains 578 mL of water. What is the volume in quarts?

10) The train traveled 500 kilometers north to Odessa in 2 hours. What is the train’s speed?

11) Ann walked 1.5 miles south to her house in 0.5 hours. What is Ann’s speed?

12)If you travel for three hours at a speed of 30 km/h, how far will you go?

13)If you are traveling at 75 km/h how long will it take to travel 32 km?

14) How long will it take to travel 78 miles if you are traveling at 65 miles per hour?

15) How many seconds will it take for a satellite to travel 450 km at a rate of 120 m/s?

16) What is the speed of a jet plane that travels 528 meters in 4 seconds?

17) After an impact involving a non-functioning satellite, a paint chip leaves the surfaceof the satelliteat a speed of 96 m/s. After 17 seconds, how far has the chip landed?

18) How long will your trip take (in hours) if you travel 350 km at an average speed of80 km/hr?

19) If a car accelerates from 3 m/s to 12 m/s in 3 seconds, what is the car's average acceleration?

20) The space shuttle releases a space telescope into orbit around the earth. The
telescope goes from being stationary to traveling at a speed of 1700 m/s in 25
seconds. What is the acceleration of the satellite?

21) A dragster in a race accelerated from stop to 60 m/s by the time it reached the
finish line. Thedragster moved in a straight line and traveled from the starting line to
the finish line in 8.0 sec. What was the acceleration of the dragster?

22) Amy uses 20N of force to push a lawn mower 10 meters. How much work does she do?

23) Frank does 2400J of work in climbing a set of stairs. If he does the work in 6 seconds, what is his power output?

24) How much work is required to pull a sled if you use 60J of work in 5 seconds?

25) How much work does an elephant do while moving a circus wagon 20meters with a pulling force of 200N?

26) If it takes 5 seconds for you to do 1000J of work, what is your power output?

27) A 900N mountain climber scales a 100m cliff. How much work is done by the mountain climber?

28) A small motor does 4000J of work in 20 seconds. What is the power of the motor in watts?

29) A woman runs a kilometer using a force of 210N and a power output of 500W. How long in minutes does it take this woman to complete 1 kilometer?

30) A deflated hot-air balloon weighs a total of 8000 N. Filled with hot air, the balloon rises to a height of 1000 m. How much work is accomplished by the hot air?