Various simple calculations

[Guest]

The formula for the force required to give a mass and acceleration is F=mxa. What is the force required if m= 5.23 kg and a=3.2m/s^2.

This is what I have done: F=mxa
F= 5.23 x 3.2
F= 16.736=17

I'm not sure what units you're suppose to put though..

Next easy question I don't remember how to do:
Convert 6580000 cm to km.
5.24 * 10^8hm to Gm

Also what are these units: hm, and this u letter..with a line haning down on the left side.., and Mm



Thanks for the help as always,
Anna

 

[wjm11]

The formula for the force required to give a mass and acceleration is F=mxa. What is the force required if m= 5.23 kg and a=3.2m/s^2.

This is what I have done: F=mxa
F= 5.23 x 3.2
F= 16.736=17

Keep your units in your calculations:

F = ma = (5.23 kg)( 3.2m/s^2) = 16.736 kgm/s^2 = 17 N (Newtons)

Note that the mass you are given has three significant digits, but the acceleration only has two. Therefore, use only two significant digits in your answer when multiplying these numbers together. That’s why we should show the final answer as 17 N.

 

[wjm11]

Convert 6580000 cm to km.

To do any type of conversion, we use “conversion factors”, which are made from things we know to be true. For example, 5280 ft = 1 mile is something we know is true, so we can make a conversion factor from this of either (5280 ft)/(1 mile) or its inverse, (1 mile)/(5280 ft). Since 5280 ft is 1 mile, this ratio is actually equal to 1, so if we multiply a number by this ratio, we’re really multiplying by 1. That means we’re not changing the value of the number, just the way it looks. Here’s an example:

100 ft (1 mile)/(5280 ft) = .018939 miles

Notice that I include the units (ft and miles) in the calculations. The ft units appear in both the numerator and denominator, so they cancel out. Since “100 ft” has ft in the numerator, I purposely chose the conversion factor that had ft in the denominator. The only units left are the miles, so that’s what appears in the answer.

If we want to convert ft/sec to mi/hr, we use one conversion factor to change feet into miles and another conversion factor to change seconds into hours:

(100 ft/s)* (1 mile)/(5280 ft)*(3600s/1 hr) = 68.182 mi/hr

Notice that ft cancels ft, and s cancels s, so the only units left are mi/hr.

Also what are these units: hm, and this u letter..with a line haning down on the left side.., and Mm

Read your book.

 

[Guest]

F = ma = (5.23 kg)( 3.2m/s^2) = 16.736 kgm/s^2 = 17 N (Newtons)

How come the units become to Newtons?

 

[stapel]

What is a "Newton"? (Look up the definition. It should say what the units in a Newton are.)

Eliz.

 

[wjm11]

How come the units become to Newtons?

That is the definition of a Newton, i.e.,

1 Newton = 1 kgm/s^2

A Newton is a unit of force. Since we are calculating a force, it is more clear and convenient to state the answer in terms of Newtons rather than leave it in kgm/s^2.