phyFinal Flashcards
Vernier caliper precision?
0.01 cm / 0.1 mm
Micrometer precision?
0.001 cm / 0.01 mm
Formula for pendulum time to complete one cycle
2π√((Length of string (m))/(Accleration from gravity))
Relationship between time period (s) and length (m)?
Time period varies as / is proportional to square root of length.
First law of motion?
Every body continues in state of rest/uniform motion unless external force acts on it.
Second law of motion formula with units?
F(N) = m(kg) x a (ms-2)
Define inertia
Reluctance of object to change its state of rest/uniform motion due to its mass.
Define terminal velocity
Maximum velocity of falling object in fluid medium, when air resistance = object weight, resultant force on object 0, object has no acceleration.
Describe parachutist motion
- Person immediately A due to gravity.
- UDF from AR increasing, A/RF decreasing.
- TV: UDF = W, A/RF 0.
- Descent continues at constant TV.
- Parachute opens, increased SA, increased UDF from AR supersedes W, deccel immediately.
- UDF decreasing, A/RF increasing.
- 2nd slower TV: UDF = W, A/RF 0.
- Descent continues at constant slower TV.
Describe how surface area and weight affects terminal velocity.
Same SA, heavier object takes longer time to reach TV, has faster TV.
Same weight, larger SA object takes shorter time to reach TV, has slower TV.
Describe stable equilibrium tilt
Object tilted, CG raised, line of action of force remains in BA, (A)CWM of weight about contact point causes it to return to original position.
Describe unstable equilibrium tilt
Object tilted, CG falls, line of action of force falls outside BA, (A)CWM of weight about contact point topples it.
Describe neutral equilibrium tilt
Object tilted, CG stays at same level, moment of weight about contact point 0, stays in same position.
Define stability
Ability of object to return to original position after it has been tilted slightly.
How to increase stability?
Lower CG (by adding load at BA)
Increase/widen BA
Define moment of a force + formula
Product of force and perpendicular distance from line of action of force to the pivot
Moment(Nm) = F(N) x D(m)
Define prinicple of moments
When body is in equilibrium, sum of CWM about pivot = sum of AWCM about same pivot.
Define conservation of energy
Energy cannot be created or destroyed, can be converted from one form to another or transferred from one body to another, but total amount in an isolated system remains constant.