Newton’s Third Law (with free body diagrams in 2D) | Starter Quiz | Oak National Academy

What is the difference between scalar quantities and vector quantities?

• Both have direction, but scalar quantities also have magnitude.

• Both have magnitude, but scalar quantities also have direction.

• Both have magnitude, but vector quantities also have direction.

• Both have direction, but vector quantities also have magnitude.

Answer explanation

Scalar quantities, such as mass, have magnitude (size) but not direction. Vector quantities, such as velocity, have magnitude and direction.

Which of the following are vector quantities?

• speed

• energy

• velocity

• distance

• displacement

Answer explanation

Velocity describes both the speed and direction of motion of an object. Displacement describes both the straight-line distance from a starting point and the direction from the starting point.

What is the meaning of the prefix ‘m’ in the units mm and mg?

• milli-

• micro-

• thousandth

• thousand

• millionth

Answer explanation

The prefix ‘m’ in front of a unit symbol stands for ‘milli-’ and means thousandth. 1 mm is one thousandth of a metre (because there are 1000 millimetres in a metre) and 1 mg is one thousandth of a gram.

What is the meaning of the prefix ‘k’ in the units km and kg?

• kine-

• kilo-

• thousandth

• thousand

• hundred

Answer explanation

The prefix ‘k’ in front of a unit symbol stands for ‘kilo-’ and means one thousand. There are one thousand metres in a kilometre and one thousand grams in a kilogram.

What is the meaning of the prefix ‘M’ in the units MW and MJ?

• mega-

• micro-

• hundred

• millionth

• million

Answer explanation

The prefix 'M' in front of a unit symbol stands for ‘mega-‘ and means million. There are one million watts in a megawatt and one million joules in a megajoule.

Which of the following lengths are equal to 8.2 m?

• 820 mm

• 8200 mm

• 82 mm

• 0.0082 km

• 0.082 km

Answer explanation

There are 1000 mm in 1 m, so 8.2 m = 8.2 × 1000 mm = 8200 mm. There are 1000 m in 1 km, so 8.2 m = 8.2 × 0.001 km = 0.0082 km.