Education
Helicopters, Parachutes And Cones
What happens?
A hollow paper fish is carried upward in a flow of air whose speed can be controlled. By pressing buttons appropriately you can make the fish hover in the air current.
How does it work?
According to Isaac Newton's First Law, an object remains stationary (or in constant straight line motion) if the sum of all the forces acting on it is zero. The downward force on the fish is its weight. From Newton's Second Law, there is an upward force equal to the rate of change of momentum of the upward moving air, from its initial speed to zero, as it hits the inside surface of the fish. When you make it hover you are providing an upward force equal to the fish's weight.
Why is it important?
If you jump out of an aeroplane without a parachute, you will accelerate downwards until you reach terminal velocity. Then you continue at this constant speed until you hit the Earth. As an object accelerates downwards due to gravity, the air resistance (drag) force opposing its motion increases, causing its acceleration to decrease. When it reaches a speed where the drag force is equal and opposite to its weight, the object stops accelerating and continues to fall at a constant speed called terminal velocity. The greater the drag, the greater is the opposition to acceleration. A parachute presents a much larger area to the air it travels through than a freely falling person, so has much greater drag and reaches a lower terminal velocity.
How does it relate to the primary curriculum?
- Curriculum objectives: Mutual understanding (if working in a pair or small group)
- Cross-curricular skills: Communication (if working in a pair or small group)
- Thinking skills and personal capabilities: Thinking, problem solving, decision making; Working with others (if working in a pair or small group)
- Area of learning - The world around us: Pupils can explore: how they interact in the world; the causes and effects of movement, forces and energy
- Learning experiences: Investigating and problem solving; Active and hands on; Enquiry based
- Attitudes and dispositions: Curiosity
How does it relat to the post-primary curriculum?
- Science: Pupils should have opportunities to: explore forces and energy transfer; develop their manipulative skills
Thinking skills
Identifying factors in the situation; Analysing elements of the situation; Drawing conclusions, or relating conclusions and reasons
Learning styles
Visual; Kinaesthetic; Spatial
Where can you find out more?
www.buzzle.com/articles/how-does-the-parachute-work.html (how a parachute works)
www.adventure.howstuffworks.com/skydiving.htm (sky diving)