When you are doing a problem like this for an example 95 km _____cm ...When its bigger to smaller do you multiply or divide and when its smaller to bigger do you multiply or divide?
2007-02-07 08:47:32 · 3 answers · asked by Anonymous in Science & Mathematics ➔ Physics
When going from bigger units to smaller units, you multiply (more small units fit into a bigger unit). When going from a smaller unit to a bigger unit, you divide (you need many small units to make a bigger unit).
2007-02-07 08:51:35 · answer #1 · answered by Chris S 3 · 1⤊ 0⤋
I find it easier to think of the problem as multiplying fractions and "cancelling" units. We know 100 cm are in a meter and 1000 meters are in a kilometer. So think of these coversion ratios as fractions: "100cm / 1 m" and "1000m / 1 km". To change kilometers to centimeters you take 95 km * (1000m / 1 km). Notice that the units of km "cancel" each other out as if "km" was a variable. That leaves you with 95*1000m = 95,000 m.
To convert this to centimeters, again used one of the fractions. 95000m * (100cm / 1 m) = 9,500,000 cm.
When you set up multiple fractions like this to let the units "cancel" and end up with the unit you want, it's sometimes called the "picket fence" method. You could to it all at once by writing:
95 km * (1000m / 1 km) * (100cm / 1 m).
It might seem like a compicated way at first, but once you get the idea it helps to keep all the units straight in your head as you try to do conversions, and you're less likely to make a mistake.
2007-02-07 08:56:10 · answer #2 · answered by Anonymous · 0⤊ 0⤋
smaller - multiply. 95km is a much higher number of cm's.
bigger - divide.
2007-02-07 08:50:49 · answer #3 · answered by Steven D 5 · 0⤊ 0⤋