Force

1. An object is at rest and stays at rest + an object at motion in a straight line stays in motion unless acted on by an outside force.

2. Net Force is defined by the sum of forces $\Sigma F=\Sigma manet$

        mass is “resistance to acceleration”

    $a=\frac{m}{s^2}$ m=kg $\left\lbrack\operatorname{kg}\cdot\frac{m}{s^2}\right\rbrack=\left\lbrack N,newtons\right\rbrack$

3. For every action there is an equal and opposite reaction

     F_N (Normal force)
                            ^
                            |
                     +--------------+
                     |              |
                     |  15 kg box   | ------> Force applied = 50 N
                     |   (ice)      |
                     +--------------+
                            |
                            v
                     F_g (Gravity)
---------------------------------------------------------
                   Ice surface (frictionless)

How long will it take to move the block of ice 10 meters when the force is angled 30^o?

$\Delta x=Vi+\frac12at^2$                  V_o =0                             F_net=ma

$10=\frac12\left(3.3\right)t^2$                                                             $50N=15\left(a\right)$

                                                                                           $3.3\frac{m}{s^2}$=a

Free Body diagram(Vector diagrams)

weight= Fw(W) =mg

push

pull

normal force=force of the surface on which an object rests, perpendicular to the surface

friction$f$ = resistive force- a force that resists motion (always opposing motion)

tension= force in a string, rope, cable, thin rod, etc. as a result of a load hanging from it

free body

-isolate object

-draw vectors to represent all forces

^

l F_T

l                                    0

0                                   l    F_w

l                                    v

l F_w

v

\ /

\ /. T

o

l

    l. F_w

   v