2. Mechanics Flashcards
Define displacement
The length and direction of the line segment joining the initial and final positions of an object
Define velocity
Rate of change of displacement
Define acceleration
Rate of change of velocity
What is the acceleration for an object travelling in the positive direction (speeding up/slowing down)?
Speeding up: Positive acceleration
Slowing down: Negative acceleration
What is the acceleration for an object travelling in the negative direction (speeding up/slowing down)?
Speeding up: Negative acceleration
Slowing down: Positive acceleration
Define positive acceleration
Velocity increasing/velocity decreasing in opp. direction
Define negative acceleration
Velocity decreasing/velocity increasing in opp. direction
What does the area under an acceleration-time graph show?
Change in velocity
Velocity may not start from zero
What are the 2 assumptions made in the kinematics equations?
- Acceleration is constant
2. When t=0, s=0
What 2 factors cause air resistance (AR) to increase?
- An increase in mass
2. An increase in speed
Define terminal velocity
The constant velocity reached by a falling object when the drag force equals in magnitude to the force that is accelerating the object
(fluid resistance is the horizontal version of this)
Define drag force
The retarding force due to air resistance
Directly proportional to the speed of the object
What does a ‘projectile motion’ graph look like?
A parabola
Difference between a no-AR graph and an AR-graph for projectile motion?
- Non-symmetrical
- Lower max height
- Shorter range
- Travels further horizontally on the way up than the way down
Describe the motion of a projectile, both horizontal and vertical
Horizontal: Uniform velocity
Vertical: Uniform acceleration
What are the 3 different types of fields, and what do they each act on?
- Gravitational - Acts on mass
- Electric - Acts on charges
- Magnetic - Acts on moving charges