Quick answer: Mass is the amount of matter in an object, measured in kilograms, and it never changes. This grade 7 science worksheet on weight and mass gives 20 problems from easy to hard: mass or weight?, the weight formula and a bag of rice on Earth. The worked answers are on a separate page, and the worksheet is a free printable PDF.
These problems train you to tell mass from weight, to use W = m × g, to rearrange it to find mass or g, and to compare the weight of an object on different planets. They start with recall and units and finish with multi-step reasoning.
They suit grade 7, Year 8 and Class 7 learners, and match NGSS middle school and early GCSE and IGCSE physics.
Level: Grade 7 science (Year 8 · Class 7) · Curriculum: MS-PS2-4
Problem 1 Mass or weight? ★★★
Copy and complete the table with the unit and the measuring instrument.1. Firstly, mass: unit ___ ; instrument ___ .
2. Then weight: unit ___ ; instrument ___ .
Problem 2 The weight formula ★★★
Write the formula that links weight, mass and gravitational field strength. State what each symbol means and give the unit of each.Problem 3 A bag of rice on Earth ★★★
Priya in Delhi buys a 5.0 kg bag of rice. Calculate its weight on Earth (g = 9.8 N/kg).Problem 4 True or false? ★★★
Say whether each statement is true or false and correct any false one.1. Firstly, mass is measured in newtons.
2. Then your mass is the same on the Moon as on Earth.
3. Finally, weight is a force.
Problem 5 Grams to newtons ★★★
Olu in Ibadan holds a 750 g mango.1. Firstly, convert 750 g into kilograms.
2. Then calculate the weight of the mango on Earth.
Problem 6 Reading the gravity chart ★★★
Use the bar chart of surface gravity.2. Then name the body with the weakest gravity.
3. Finally, state the value of g on Venus.
Problem 7 Bathroom scale ★★★
Hana in Seoul steps on a bathroom scale that shows 48 kg.1. Firstly, state whether 48 kg is a mass or a weight.
2. Then calculate the force of gravity on Hana in newtons (g = 9.8 N/kg).
Problem 8 Rover on Mars ★★★
A rover has a mass of 180 kg. The diagram shows it on Earth and on Mars.2. Then calculate its weight on Mars (g = 3.7 N/kg).
3. Finally, state its mass on Mars.
Problem 9 Mass from weight ★★★
A spring scale shows that a box weighs 245 N on Earth. Calculate the mass of the box.Problem 10 Planet X graph ★★★
Liam in Dublin plots the weights of different masses on an unknown planet.2. Then calculate the gradient of the line.
3. Finally, use the table in the lesson to name the planet.
Problem 11 Earth against Jupiter ★★★
A 2.0 kg object is taken from Earth to Jupiter (g = 24.8 N/kg).1. Firstly, calculate its weight on each planet.
2. Then calculate how many times heavier it feels on Jupiter, to one decimal place.
Problem 12 Jumping on the Moon ★★★
Daniel in Kampala watches a video of an astronaut jumping very high on the Moon.1. Firstly, explain why the astronaut can jump higher than on Earth.
2. Then state what happens to the astronaut’s mass during the trip.
Problem 13 Reading a spring scale ★★★
A bag hangs from a spring scale that reads 14.7 N on Earth.1. Firstly, calculate the mass of the bag.
2. Then calculate what the scale would read on the Moon (g = 1.6 N/kg).
Problem 14 Complete the table ★★★
Calculate the missing values.Row 1: 3.0 kg on the Moon (g = 1.6 N/kg), weight ?.
Row 2: 8.0 kg on Venus (g = 8.9 N/kg), weight ?.
Row 3: mass ? on Earth with weight 98 N.
Problem 15 Spot the error ★★★
Sofia in Cape Town says: “An astronaut with a weight of 80 kg on Earth has a weight of 13 kg on the Moon.”1. Firstly, find two mistakes in her statement.
2. Then give the correct values if 80 kg is the astronaut’s mass.
Problem 16 Lifting a container ★★★
A crane lifts a container of mass 250 kg.1. Firstly, calculate the weight of the container (g = 9.8 N/kg).
2. Then the cable pulls up with 3000 N. Calculate the net force and give its direction.
3. Finally, describe the motion of the container.
Problem 17 Three worlds ★★★
An object weighs 117.6 N on Earth.1. Firstly, calculate its mass.
2. Then calculate its weight on Jupiter (g = 24.8 N/kg).
3. Finally, calculate its weight on the Moon (g = 1.6 N/kg).
Problem 18 Mystery planet ★★★
A space probe of mass 4.0 kg weighs 30 N on the surface of a newly discovered planet.1. Firstly, calculate g on that planet.
2. Then state which two planets from the lesson table it lies between.
3. Finally, calculate the weight of a 10 kg rock there.
Problem 19 Hammer and feather ★★★
On the Moon, a 1.3 kg hammer and a 0.0030 kg feather are released together and land at the same time.1. Firstly, calculate the weight of each on the Moon (g = 1.6 N/kg).
2. Then explain why they land together even though the weights are different.
3. Finally, explain why the feather falls more slowly on Earth.
Problem 20 Scale on the Moon ★★★
A bathroom scale on Earth converts force to mass by dividing by 9.8 N/kg. Amara, whose mass is 50 kg, stands on this scale on the Moon (g = 1.6 N/kg).1. Firstly, calculate the force the scale feels.
2. Then calculate the reading the scale shows.
3. Finally, explain why the reading is misleading.
