Physics: 5 Forces Flashcards
What is a vector quantity?
Magnitude and direction
What is a scalar quantity?
Magnitude only (no direction)
What are three basic examples of contact forces?
- Friction
- Air resistance
- Normal contact force
What are three basic examples of non-contact forces?
- Gravity
- Magnetic
- Electrostatic
What would the free body of a car look like?
Up arrow = upthrust
Down arrow = gravity (weight)
Left arrow (back of car) = friction
Right arrow (front of car) = driving force (thrust)
What would the free body diagram of a boat look like?
Up = Upthrust
Down = Gravity (weight)
Left (back of boat) = water resistance
Right (front of boat) = driving force (thrust)
What would the free body diagram of a plane look like?
Up = lift
Down = gravity (weight)
Left (back of plane) = air resistance
Right (front of plane) = driving force (thrust)
What would the free body diagram of a skydiver look like?
Up = Air resistance
Down = gravity (weight)
What happens when the resultant forces of an object are the same?
The object is at equilibrium - it is either stationary or moving at a constant speed.
What is inelastic deformation?
When an elastic object is stretched or compressed and does not return to its original shape once the force is removed.
What is elastic deformation?
When an elastic object is stretched or compressed but returns to its original shape once the force has been removed.
What is the point at which an object becomes inelastically deformed called?
The limit of proportionality
What does each line in a distance time graph mean?
- Straight diagonal line: constant speed - the steeper the line the faster the constant speed.
- Straight horizontal line: stopped
- Curved upwards line: accelerating
- Curved downwards line: decelerating
What does each line in a velocity time graph mean?
- Straight diagonal line: constant acceleration - the steeper the line the faster.
- Straight horizontal line: constant speed
- Curved upwards line: increasing acceleration
- Curved downwards line: gradual deceleration
What is the concept of terminal velocity?
When the upwards force and the downwards force balance out (e.g. skydiving) - results in object moving at constant speed downwards (no acceleration).
What is Newton’s first law?
An object will remain in motion until an [unbalanced] external force acts upon it.
What is Newton’s second law?
F = ma
What is Newton’s third law?
Every force has an equal and opposite reaction force.
