Question

The sun is 1.5 x 10^11 m from earth.
Express this distance with an SI prefix.

Answer 1

First, we write the SI prefixed.

The SI unit for distance is meters.

Kilo = 10³

Mega = 10⁶

Giga = 10⁹

Terra = 10¹²

Because our value has ten to the power of 11, we will use the closest and lowest power prefix, which is giga.

1.5 x 10¹¹ / 10⁹

= 1.5 x 10² Gm or 150 Gm

Little more explanation : In scientific notation, if the exponent of 10 is positive, the number is very very large. In the metric system, very large numbers are expressed in megameters (Mm) or gigameters (Gm). Gigameters is equal to 10⁹ meters. So, in SI prefix, that would be equal to 150 Gm. In kilometers, that would be equal to:

1.5×10¹¹ m * (1 km/1000 m) = 1.5×10⁸ km

Ref: Web

Answer 2

First, we write the SI prefixed. The SI unit for distance is meters.

Kilo = 10³

Mega = 10⁶

Giga = 10⁹

Terra = 10¹²

Because our value has ten to the power of 11, we will use the closest and lowest power prefix, which is giga.

1.5 x 10¹¹ / 10⁹

= 1.5 x 10² Gm or 150 Gm

Writing in kilometers, we simply repeat the procedure except we divide by 10³ this time.

1.5 x 10¹¹ / 10³

= 1.5 x 10⁸ km

Explanation: