Help me understand these motion equations, what does (t) stand for here??

Question

dtan5457 · Answer

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giantrobot · Answer

t is time, displacement is velocity*time.

irishboy123 · Answer

these are the equations of motion http://www.bbc.co.uk/bitesize/higher/physics/mech_matt/analyse_motion/revision/2/ and the distance formula http://www.purplemath.com/modules/distform.htm

dtan5457 · Answer

I don't get if I solve for t or what though...

like for df on the 2nd page, what did they plug in for "t" to get the dfmin and dfmax?

yylamon99 · Answer

t is time

dtan5457 · Answer

I get that t is time but I don't see how that works here

festinger · Answer

Use equation 2 to substitute as t in equation 1:
$$y(t)=-g\frac{t^2}{2}+V_0 (Sin \theta) t+h_0 $$ since $h_0 =0$ and we want $y(t)=0=h_0$ so we have: $$t=\frac{2 V_0}{g} (Sin \theta)$$ Substituting this expression into equation 1:$$x(t)=d=V_0 (Cos\theta ) t = V_0 (Cos\theta) \frac{2V_0 (Sin\theta)}{g}=\frac{2V_{0}^{2}Sin\theta Cos \theta}{g}$$ If we use the double angle formula $Sin2\theta =2Cos\theta Sin\theta$ we arrive at the desired equation: $$d=\frac{V_{0}^{2} (Sin2\theta)}{g}$$

astrophysics · Answer

It means it's a function of time, x(t) displacement as a function of time.

physics_dude99 · Answer

these are the 2D kinematic equations for motion with constant acceleration.  Sometimes these are called Projectile Motion if gravity is the only force acting.

dtan5457 · Answer

So what was the value of t that led the book to get 7.77 dfmin and 7.82 dbmin?