0.17 Phy1150: force and motion -- units of force  (Page 4/9)

The algebraic solution

Once you work through the algebra for this problem, you will have determined that the answer to the problem is given by the following expression:

centripetal force = 2kg * (5/s) *(3m/s)

Let Google do the work

Enter the following expression into the Google search box and press the Enter key:

2kg * (5/s) *(3m/s)

The following text should appear immediately below the search box.

2 kg * (5 / s) * (3 (m / s)) = 30 newtons

Note that in this case, I used the correct symbols for SI units.

Do it again with the units spelled differently

Enter the following expression into the search box and press the Enter key.

2 kilograms * (5 radians/second) * (3 meters/second)

The following text should appear immediately below the search box.

2 kilograms * ((5 radians) / second) * (3 (meters / second)) = 30 newtons

Do it one more time

Let's do it one more time, this time mixing metric and English units. Enter the following expression into the search box and press the Enter key.

2 kilograms * (5 radians/second) * (9.8425197 feet/second)

The following output should appear below the search box:

2 kilograms * ((5 radians) / second) * (9.8425197 (feet / second)) = 30 newtons

The conclusion

Given an input with units in the correct format, the Google calculator is not only able to deal with those units and perform the calculation correctly, it is also able to properly convertthe result to the correct value in derived units (newtons in this case).

Other units

When analyzing a physics problem, the safest approach is probably to convert all of the given information into SI units and solve the problem in SI units,converting the result back to some other system of units if required. However, some textbooks and some physics professors may not allow that approach.Therefore, you need to know something about the other units of force that you may encounter.

poundal

As you learned in an earlier module, the pound is a unit of mass.

There is a very handy online mass unit converter at (External Link) . However, I don't know if it is accessible for screen readers and Braille displays. According to thatconverter,

1 pound = 0.45359237 kilograms

Can use Google for conversion

Even if that converter isn't accessible, you can use the Google calculator to make such conversions. Enter the following in the Google search box and press the Enter key:

conversion pound to kilogram

The following text should appear immediately below the search box:

1 pound = 0.45359237 kilograms

The foot

A foot is a unit of length commonly used for measurements in the United States.

1 foot = 0.3048 meters

The poundal unit of force

A poundal is a unit of force that causes a mass of one pound to accelerate at one foot per second squared (1 ft/s^2).

Because the poundal and the newton are both units of force, we can convert from one to the other as follows:

1 poundal = 0.138254954 newton

dyne

The gram is another unit of mass and the centimeter is another unit of length.

1 gram = 0.001 kilogram

1 centimeter = 0.01 meter

The dyne unit of force