Topic 2.1: Motion II Flashcards
What is displacement?
Displacement is the distance given in a direction from a starting point to a ending point
What is acceleration?
Acceleration is rate of change of velocity
When can you use the equations of motion?
For motion in a straight line (and for motion in parabolas)
found in data booklet
What is gravity?
Acceleration of freefall due to a planet’s gravitaion field
The force acting on a 1kg mass due to a planets gravitational field
What is Earth’s gravity?
g = 9.81
Do all objects fall at the same acceleration?
Yes. All objects fall at the same acceleration due to gravity
Why do objects dropped at the same time reach the ground at different times?
Air resistance increases as speed increases which causes a decreasing acceleration between gravity and 0.
So, if an object falls for long enough its acceleration will eventually become 0 due to air resistance
Eventually, the air resistance is equal to the downwards weight force, so they end dup balancing each other out. Due to no resultant force the object falls at terminal (constant) velocity
What is fluid resistance?
Fluids (i.e gases and liquids) oppose the motion of bodies passing through them as a frictional force
What is the formula for fluid resistance at SLOW speeds?
F = kv
F ∝ v
What is the formula for fluid resistance at HIGH speeds?
F = kv²
F ∝ v²
What can the formulas for fluid resistance tell us?
Fluid resistance force increases until it equals the forward motion force and the body travels at constant maximum terminal velocity
What is upthrust / buoyency?
Upthrust is the upwards force on a body that is partially or fully submerged in a fluid (liquid or gas)
Upthrust is a major force that explains why ships float and how helium airships rise in the air
