Unit 3 Flashcards
Define elastic
materials that springs back to its original shape when bended or stretched
Define plastic
materials that keep its new shape when bended or stretched
Define load
The force applied to a spring
Define extension
difference between stretched and unstretched lengths
how do we know if a material obeys Hooke’s law?
if, beneath its elastic limit, the extension is proportional to the load
What is the formula for the load?
load=spring constant x extension (F=k x X)
what is always the spring constant?
0.1N/mm
Define elastic limit
the point where below the point, the spring is elastic but beyond the point, a spring is permanently stretched (plastic)
define mass
property of all matter that creates gravitational fields
define weight
the force pulling a mass towards another mass
what force is friction?
contact force (2 bodies must touch)
define linear
straight line
define force
push of pull on an object that attempts to change its motion, shape, or size
name 4 forces (push and pull)
-physically pushing and pulling an object
-magnets pushing and pulling
-electric charges pushing and pulling
-gravitational forces pulling objects together
define inertia
capacity of an object to resist a change in motion from a force (for example, sudden jam of breaks in a bus is inertia)
define momentum
physical ability, stamina in a weight
how many forces are in a moving free body diagram, what are they, and what direction are the forces applied?
6, air resistence <–, Friction <–, movement –>, drive force –>, reaction force (up), weight (down)
how many forces are in a stationary free body diagram? what are they and what direction are the forces applied?
2, reaction force (up), weight (down)
how do you find the net effect of forces (total force) when 2 forces are applied in the same direction?
add the 2 magnitudes (forces) (SI unit = N)
how do you find the net effect of forces (total force) when 2 forces are applied in the opposite direction?
subtract the 2 magnitudes (forces) (SI unit = N)
how do you find the net effect of forces (total force) when 4 forces are applied NESW?
like the 2 forces in opposite direction, subtract the 2 forces opposite of each other (SI unit = N)
how do you find the net effect of forces (total force) when 1 force is applied north and 1 force is applied east?
the total force is the diagonal line in between so, you use Pythagorean theorem and find the diagonal line’s force (SI unit = N)
if you throw a ball out at the force of 20N, which direction is the force applied?
west or east
define fluids
things that flow
when does friction occur?
when 1 object is being pul.ling or pushed while in contact with another object
what energy does kinetic energy convert to during friction?
heat energy
when does air resistance occur?
when an object is moving through the air
define drag force
opposing force on the object’s moving through fluids
when speed increases, what happens to the air resistance and drag force?
increases
why cant objects accelerate?
air resistance
if a ball has a mass of 5kg, what is its weight?
50N
What is the relation between net force, mass, and acceleration?
Net force = mass x acceleration (FAM TRIANGLE)
If the acceleration is 0 of an object, what speed is the object moving at?
steady speed/constant speed
define terminal speed
acceleration is 0/constant speed/steady speed
define terminal velocity
the constant velocity of a falling object when the force of air resistance is equal in magnitude and opposite in direction to the force of gravity (gravity and air resistance is the same)
define Equilibrium
total force is 0, no change in motion, if it’s at rest it stays at rest, if it’s in motion it remains at that motion with the same speed (when forces are equal and cancel each other out)
define torque
force
define force
brings change in state of motion in an object (push and pull on an object)
describe movement of a force
rotational effect (turning effect) brought on a body due to application of force
how do you find the movement/momentum of a force?
M = length x force (applied) (SI unit = N/m)
define movement of a force
product of the force and the perpendicular distance from the pivot to the line of action of the force
is the movement of a force a scalar or vector?
Vector (need to include if it is moving in clock wise or anti clock wise)
what is the relationship of the clockwise moment and the anti clockwise moment for the rod to not rotate?
clockwise and anti clockwise movement must be equal
what is the principle of moments?
it states that if a body is not to rotate, the net clockwise moment of a force on it must equal the net anti clockwise moment of a force
what is the formula for making the rod straight if the rod is tilted and has a weight?
(length of pivot to center of gravity x weight) = (length of pivot to end the rod is tilted x F)
define the center of gravity
the point on a body where the whole of the weight of the object is assumed to be acting
what is the relationship between the center of gravity and stability?
position of the center of gravity has a affect on the stability of objects
relationship between base area and stability?
more base area, more stability
relationship between height and stability?
height smaller, more stability (closer to ground, more stable)
how do you find out the total moment of a force in a negligible mass rod with the pivot in the center?
(M = f1 x length) + (M = f2 x length)
is clockwise positive or negative number?
negative
is anti clockwise positive or negative number?
positive
what is the formula for creating a balanced rod (pivot in middle)?
50x = 40
->40/50
->0.8m
how do you find out how much the rod tilted/what the length is to make the rod balanced if the pivot is not in the middle and it has a weight?
smaller side = length x force
larger side = (weight x length from pivot to CG) + (all large side length of ride x force)
-unit depends on what you’re finding out
is the force applied on the right of the rod anti clockwise or clockwise force?
clockwise
is the force applied on the left of the rod anti clockwise or clockwise force?
anti clockwise
