WASSCE Physics · Paper 1 style

Mass and weight

One sample question with the full working. 1 more in the app, with instant feedback and repair sessions for the traps below.

The weight of a 5 kg bag on Earth (g = 10 m/s²) is

A5 N
B0.5 N
C5 kg
D50 N

Show the answer and working

Answer: D

W = mg = 50 N.

Trap A Confuses mass and weight: Weight is a force: W = mg (N). Mass (kg) is the amount of matter and does not change with g.

Trap B Inverts a formula: Write the defining equation in words first (density = mass per unit volume), then rearrange algebraically. Check units: kg/m³.

Trap C Writes a quantity in the wrong unit: Carry units through every line. A percentage is a ratio × 100; joules and newtons cannot become % without dividing by a quantity of the same kind.

Traps in Mass and weight

Confuses mass and weight
Weight is a force: W = mg (N). Mass (kg) is the amount of matter and does not change with g.
Inverts a formula
Write the defining equation in words first (density = mass per unit volume), then rearrange algebraically. Check units: kg/m³.
Writes a quantity in the wrong unit
Carry units through every line. A percentage is a ratio × 100; joules and newtons cannot become % without dividing by a quantity of the same kind.

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