Unit 5: Forces and Motion

Newton’s first law

States that an object at rest stays at rest, and an object in motion remains in motion at a constant velocity unless acted upon by a net external force.

Newton’s second law

F = ma

Fg

is the gravitational force acting on an object

Fn

is the normal force exerted by a surface on an object resting on it, perpendicular to the surface.

Ff

is the force that opposes the relative motion of two surfaces in contact.

Ft

is the tension force transmitted through a string, rope, or cable when it is pulled tight by forces acting from opposite ends.

Fd

is the drag force acting opposite to the relative motion of an object moving through a fluid or gas

Fs

exerted by something stretchy trying to return to its original shape

Fe

exerted b/w two charged objects. + and + or - and - will repel, + and - will attract

Fmag

exterted b/w two magnetic objects. N and N or S and S will repel, N and S will attract

Mass

amount of matter in an objects

Other word for mass

inertia

Weight

Force of gravity pulling on a mass (Newtons)

Net force always has…

DIRECTION

Acceleration

Rate of change of velocityover time.

Acceleration ONLY is speeding up when the net force and velocity are in the _____ direction

same

how to calculate acceleration

\frac{\Delta v}{\Delta t}

Speeding up (positive direction): Pos. vs. Time

Speeding up (negative direction): pos vs time

Slowing down (positive): pos vs time

Slowing down (negative): pos vs time

Speeding up (positive): velocity vs time

Speeding up (negative) velocity vs time

Slowing down (positive) velocity vs time

Slowing down (negative) velocity vs time

Speeding up (positive) acceleration vs time

Speeding up (negative) acceleration vs time

Slowing down (positive) acceleration vs time

Slowing down (positive) acceleration vs time

Work

change in energy of an object, W = Fd

When work is done on an object, energy is ___ or ___ from the system

Added or removed

newton’s third law

every action has an equal and opposite reaction

Force of gravity: if one mass doubles what happens to the force?

Doubles

Force of Gravity: When both masses double what happens to the force

4x

Force of Gravity: If one mass doubles and the other triples, what happens to the force?

5x

Force of Gravity: How does dist. affect force?

If dist. doubles = force does 2²x. if dist. halves, force divides by 2²

Difference b/w Fg, g, and G

Fg = force of gravity

g = gravitational force

G = universal grav. constant

Equation for Fg (Coloumbs law but not)

Fg = G(m1*m2/d²)

Coloumbs law

Fe = k(q1*q2/d²)

Displacement

Δx, how far an object moves from a starting position

Three ways to change acceleration

Increase speed, decrease speed, change direction

_____ is an object’s resistance to a change in its motion

inertia