Physics 20 - Practice - Core Skills

True or False: Kinematics not only tells us HOW things move, but WHY things move.

• True
• False

How many significant digits are in: 0.0013 seconds?

• 1

• 2

• 3

• 4

Answer explanation

The "leading zeros" before any real digits appear do not count!

How many significant digits are in: 2.04 x 10³ minutes?

• 1

• 2

• 3

• 4

Answer explanation

For scientific notation, you only include the significant digits in the first part of the number BEFORE the "x" symbol.

How many significant digits are in 500.007 km?

• 1

• 2

• 3

• 6

Answer explanation

For scientific notation, you only include the significant digits in the first part of the number BEFORE the "x" symbol.

Add the two measured quantities together and type in the answer with the correct number of significant digits:

0.035 + 2.119 = ?

Answer explanation

The answer must have the same SD's as the worst measurement (0.035 has 2 SD's and 2.119 has 4 SD's).

Add the numbers together, then round it to 2 SD's.

Multiply the measured quantities together and type in the answer with the correct number of significant digits:

0.050 x 6.0001 = ?

Answer explanation

The answer must have the same SD's as the worst measurement.

0.050 has 2 SD's, so your answer should also have 2 SD's.

Which of the following correctly shows the number 209 000 in scientific notation?

• 209 x 10³

• 2.09 x 10⁵

• 0.209 x 10⁶

• 20.9 x 10⁵

Answer explanation

The leading number in scientific notation should always be a singular number, then a decimal place.

The speed of light is very fast - in fact, it's 299 792 458 m/s!

Round, using scientific notation, the speed of light to 3 significant digits.

• 2.99 x 10⁸

• 299 x 10⁸

• 3.00 x 10⁸

• 3.01 x 10⁸

Answer explanation

The leading number in scientific notation should always be a singular number, then a decimal place.

If I convert 250 km to m, the number portion of the quantity becomes

• Bigger

• Smaller

Answer explanation

km --> m means going "bigger to smaller" unit. So, you will have more of them (a bigger number).

If I convert 455 mm to m, the number portion of the quantity becomes

• Bigger

• Smaller

Answer explanation

mm--> m means going "smaller to bigger" unit. So, you will have less of them (a smaller number).