Grade 5 · Science · Unit 4 of 6
Forces in Flight
Lift, weight, thrust and drag
What your child practises
The four forces of flight (lift and weight, thrust and drag) and how they balance for a bird, a kite or a plane, plus examples of technologies, including traditional ones, that use them.
Alberta Curriculum learning outcome: 5E 1.1 · how thrust, drag, lift and weight affect flying living things and objects
Sample questions
A taste of this unit. In the app, questions change every time and get easier or harder to match your child.
Question 1
Which force acts against the direction a bird flies?
💨- lift
- drag
- gravity pulling it up
- thrust
Show answer
drag
Hint: Drag is the force of air pushing back against a moving thing.
Question 2
Lift and weight are…
- forces that only act in water
- both forces that point down
- opposing forces
- the same force
Show answer
opposing forces
Hint: Lift pushes up and weight pulls down.
Question 3
Which force holds a plane up in the air?
✈️- drag
- friction with the ground
- weight
- lift
Show answer
lift
Hint: Lift is an upward force that acts to overcome weight.
Question 4
A paper plane flies straight and level at a steady height. What is true about lift and weight?
- There is no weight
- Lift is much bigger
- They are balanced
- Weight is much bigger
Show answer
They are balanced
Hint: At a steady height, the up and down forces are balanced.
Question 5
A skydiver opens a parachute. What happens to drag?
- Thrust increases
- Drag disappears
- Drag increases, so falling slows down
- Weight disappears
Show answer
Drag increases, so falling slows down
Hint: A wide parachute catches more air, so air pushes back harder.
Question 6
Which design feature of a bird helps it have strong lift?
- a flat belly
- broad, curved wings
- short, straight claws
- thick, heavy bones
Show answer
broad, curved wings
Hint: Wing shape affects how much lift air produces.