FM1 - The three laws of motion Flashcards
Around what time did Isaac Newton work out the three laws of motion?
Around the time of the Great Plague in the 1660s
What is the first law?
Balanced forces mean no change in velocity
If a train/car is moving at a constant velocity…
The forces must be balanced
What must there be to keep a train going at a steady pace?
Zero resultant force
What is the second law of motion?
If there is an unbalanced force, then the object will accelerate in that direction
What will an unbalanced force (resultant force) always produce?
Acceleration
What are the five forms acceleration can take?
- Starting
- Stopping
- Speeding up
- Slowing down
- Changing direction
The bigger the force…
The greater the acceleration or deceleration
The bigger the mass…
The smaller the acceleration
To get a big mass to accelerate as fast as a small mass…
You need a bigger force
What is an unbalanced force often called?
The resultant force - produces acceleration
What is the equation linking force, mass and acceleration?
F = m x a
What is the third law of motion?
If object A exerts a force on object B then object B exerts the exact opposite force on object A
Use the third law of motion to explain skater A (mass 55kg) and B (mass 65kg) pushing against each other
When skater A pushes on B, she feels and equal and opposite force from skater B. Both skaters feel the same sized force in opposite directions and accelerate away from each other. However skater A will be accelerate more than B as she has smaller mass
(f = ma)
How is the third law of motion applied in swimming?
You push back against the water with your arms and legs, and the water pushes you forwards with an equal-sized force in the opposite direction
