Force and Newton's law study guide Flashcards
Force
A push or a pull
what causes an acceleration
a net force
difference of contact force and field force
Contact forces are exerted through contact and field forces are exerted without contact. Examples of contact force include pushing or pulling an object. Examples of a field force include gravitational forces and electromagnetic forces.
Newton’s first law
“an object that is at rest will remain at rest and an object that is moving will continue to move in a straight line with constant speed if and only if the net force acting on that object is zero”
inertia
the tendency of an object to resist changes in velocity; why objects with a greater mass tend to resist a change in motion more than those with a lesser mass
force and acceleration have a ______ relationship
directly proportional
The great the force, the greater the _______
acceleration
what does it mean to have a direct and an inverse relationship in an equation?
Direct- y increases, x increases
Inverse- Y increases, x decreases; x increases, y decreases
Ex.) y = a/x, y is direct with a, it’s inverse with x
Newton’s second law equation and units
Newton’s second law states that the acceleration of an object is directly related to the net force and inversely related to its mass.F = MA
Units: N
Equation for weight and units
W=MG
kg x m/s^2 –> N
6 common forces
friction, thrust, normal, weight, spring, tension
What does it mean by net force? Example?
A net force is the vector sum of ALL forces acting on an object
EX: If one person pushes a box up with 40 N and someone pushes the same box forward with 30 N, the net force is 70 N
equilibrium
When there is zero net force, meaning there is zero acceleration
Newton’s third law
all forces come in pairs, For every action there is always an equal (magnitude) and opposite (direction) reaction
Interaction Pair examples
student pulls a desk, desk pulls student; jevon sneed throws ball forward by exerting a force with hand on a ball, ball pushes back on hand
Normal Force
the perpendicular contact force that a surface exerts on another surface
Value of gravity on earth?
9.8 m/s^2
Value of gravity on moon?
1.625 m/s^2
Isaac Newton’s accomplishments
- President of Royal society and knighted in 1705
- Worked out the 3 laws of motion
- Born same year Galileo died
- wrote Principia Mathematica Philosophiae Naturalis
- At 46 was elected member of Parliament
- Discovered white light is composed of all colors of the rainbow
- Discovered Law of Universal gravitation extending to the moon and beyond
Galileo Galilei’s accomplishments
- Remembered for his work in astronomy, math, & physics
- Showed that falling objects DO NOT have velocities proportional to their weight
- Found “mountains” on the moon
- Discovered 4 of Jupiter’s moons
- Saw imperfect spots on the sun
- “Eppur si muove”
- Discovered gravity (WITHOUT air resistance) acts the same on everything
how does acceleration of an object change in relation to its mass?
Inversely proportional
If the force acting on a cart doubles, what happens to the cart’s acceleration?
It doubles
Label deck, wingwall, abutment, beams and pier on bridge
Deck: piece of the bridge you walk on
Abutment: Support at the ends of the bridge, usually made of concrete
Piers: vertical structure supports placed between abutments
Beams: Horizontal beam that is supported at each end by piers
Wingwall:the wing walls are adjacent to the abutments and act as retaining walls
What bridge have many people tried to end their life on?
Golden Gate Bridge
What’s the apex stone in the arch that locks all the stones into position?
Keystone
What is the strongest geometric shape?
triangle
What river does the London Bridge cross?
River Thames
Beam Bridge
Piers support beams that support spans of concrete slabs, most common & least expensive
Arch Bridge
Weight of bridge is transferred along the arch to piers & abutments
Suspension Bridge
Have two towers that support main cables, used to span long distances
Truss Bridge
A triangular framework used above or below to support bridge
Cantilever Bridge
Beams extend from each end of the bridge
Movable Bridge
Bridges are designed so that a portion of it can be moved to allow large water vessels to pass underneath
Tacoma Narrows Bridge
Bridge that collapsed in a windstorm due to flutter, called Galloping Gertie, built in WA in the 1940s
Brooklyn Bridge
Suspension bridge in NY, Engineer building it died in a bridge related accident, son finished the building, took 14 years and 30 lives, first truly modern bridge
Golden Gate Bridge
A suspension bridge spanning the Golden gate, the opening of San Francisco bay into the Pacific Ocean
How did the rocks on Racetrack Playa move?
They moved due to sheets of ice that were blown by light gusts of wind and and pushed against the rocks causing them to slide
Why was gravity and high winds ruled out for finding out how the rocks moved?
Gravity was ruled out because the rocks moved up a slight slope, not downhill. High winds were ruled out because larger rocks would oftenly move further than smaller rocks.
Interaction Pairs
a set of two forces that are in opposite directions, have equal magnitudes and act on different objects.
