Physics Q - Typing it up.

Question

Shadow · Answer

In Biology, a common activity is dropping a meter stick to assess one's reaction time. In this exercise a person drops the stick starting at position zero while the other person grabs it as soon as they see it fall. They record the distance the meter stick falls between one's fingers before it's grabbed. Reaction time is then calculated using an equation that looks like...

$$t = 0.452 \sqrt h$$
Where h is the distance dropped in meters.

Starting with a fundamental kinematic equation, derive this equation. Use g = 9.80 m/s^2 
(Hint: the meter stick starts from rest.)

$$h = v_{0}  t + \frac{ 1 }{ 2 } a t^2$$
$$h = \frac{ 1 }{ 2 }(9.8)t^2$$
$$h = 4.9 t^2$$

Shadow · Answer

@Vocaloid What magic do they do to get it like this

$$t = 0.452 \sqrt h$$

#OutOfPractice ._.

Vocaloid · Answer

if you understand up to this point

h = 4.9t^2

divide both sides by 4.9

h/4.9 = t^2

then take the square root of both sides

t = sqrt(h)/ sqrt(4.9) which is 0.452sqrt(h) after chucking it into a calculator and rounding to three digits

Shadow · Answer

yeah I don't get that last part

Shadow · Answer

Clearly some math concept I have long forgotten x.x

Vocaloid · Answer

have to remember your exponent rules

|dw:1537160468436:dw|

Vocaloid · Answer

1/sqrt(4.9) is about 0.452ish

Shadow · Answer

Yep, that's what I forgot. Thanks (: