Gravitational force and weight | Science | Quizalize & Oak National Academy

Starter quiz

How can a force acting on an object be shown on a diagram?
- An arrow pointing to where the force is acting on the object.
- An arrow starting on the object and pointing to the direction the force acts. ✓
- A straight line joining the object to the force.
Which of these forces pulls objects towards the centre of Earth?
- tension
- normal reaction force
- gravitational force ✓
- electric force
- magnetic force
How should a force arrow for the gravitational force acting on a football be drawn?
- Starting in the centre of the football. ✓
- Starting in the bottom of the football.
- Starting in the top of the football.
- Pointing downwards. ✓
- Pointing upwards.
What property does this top pan balance measure?
- force in grams
- weight in grams
- mass in grams ✓
- mass in newtons
The figure shows a hand holding a small metal block. The metal block is not moving. Which statements are correct?
- There are no forces acting on the metal block.
- There is no resultant force acting on the metal block. ✓
- There is an upwards support force acting on the metal block. ✓
- There is a gravitational force is acting on the metal block. ✓
- The metal block has no mass.
An astronaut is walking on the Moon carrying a hammer. What will happen to the hammer if they let go of it?
- The hammer will float off upwards, getting faster and faster.
- The hammer will float exactly where it was released.
- The hammer will fall towards the Moon's surface at a constant speed.
- The hammer will fall towards the Moon's surface, speeding up as it falls. ✓

Exit quiz

Match the key words to their definitions:
- gravitational force
  
  ⇔
  
  A force that pulls objects towards the centre of planets. ✓
- mass
  
  ⇔
  
  The amount of material (matter) in something. ✓
- gravitational field strength
  
  ⇔
  
  The force on each kilogram due to gravity. ✓
- newton
  
  ⇔
  
  The unit used for force. ✓
- newtons per kilogram
  
  ⇔
  
  The unit for gravitational field strength. ✓
Starting with the smallest, sort these in order of mass.
- 1
  
  ⇔
  
  0.2 g
- 2
  
  ⇔
  
  25 g
- 3
  
  ⇔
  
  200 g
- 4
  
  ⇔
  
  0.25 kg
- 5
  
  ⇔
  
  2 kg
- 6
  
  ⇔
  
  20 kg
An astronaut takes a flag pole from Earth to the Moon with them. Which of the following are true?
- The mass of the flag pole stays the same. ✓
- The mass of the flag pole decreases.
- The mass of the flag pole increases.
- The weight of the flag pole stays the same.
- The weight of the flag pole decreases. ✓
An alien weighs themselves on the surface of some of the moons in our solar system. Starting with the smallest, list the locations into the order of the weight recorded.
- 1
  
  ⇔
  
  Umbriel (g = 0.20 N/kg)
- 2
  
  ⇔
  
  Ariel (g = 0.27 N/kg)
- 3
  
  ⇔
  
  Oberon (g = 0.34 N/kg)
- 4
  
  ⇔
  
  Triton (g = 0.77 N/kg)
- 5
  
  ⇔
  
  Callisto (g = 1.2 N/kg)
- 6
  
  ⇔
  
  Ganymede (g = 1.4 N/kg)
- 7
  
  ⇔
  
  Io (g = 1.8 N/kg)
A space probe has a mass of 954 kg and is being sent to land on the moon Europa, which has a gravitational field strength of 1.31 N/kg. How much will it weigh on Europa?
- 728 N
- 955 N
- 953 N
- 1.25 N
- 1.25 kN ✓
An astronaut with mass 652 kg lives on Mars. They weigh themselves and find that they weigh 2420 N. What is the gravitational field strength?
- 3.71 N/kg ✓
- 1.58 N/kg
- 0.27 N/kg
- 8.94 N/kg
- 0.37 N/kg

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Lesson Details

Key learning points

The mass of an object is measured in kilograms.
A force of about 10 N is needed to lift 1 kg on Earth.
On Earth, a 1 kg mass pushes down on a surface with a force of about 10 N.
There are 1000 g in 1 kg.
Gravitational force, W = m × g

Common misconception

Pupils often mix up the terms for weight and mass and use weight when they mean mass and vice versa.

Teach pupils that a force lifts objects against the pull of gravity before introducing the term weight.

Keywords

Gravitational force - The force that acts on an object inside a gravitational field.
Mass - The amount of matter (material) in an object.
Gravitational field strength - The force per kilogram caused by a gravitational field.
Newton (n) - The unit for force.
Newtons per kilogram (n/kg) - The unit for gravitational field strength.