Physics 3.5.4d - Projectile Practice Problem 4

Practice Problem on Projectile Motion

[derekowens]

If the acceleration (which is down) is positive, that means that as you work the problem, every vector pointed down must be positive, and every vector pointed up must be negative. So your initial velocity would be negative, and you would end up getting a negative value for the maximum height.

[wakawu]

thank you i was struggling a bit with a very similar problem and this cleared all of my questions up. BRAVO! keep it up you are helping hundreds like me everyday no doubt

[sea]

Thanks alot, finally starting to get these right!

[atlass]

May GOD bless you!! you are a fantastic teacher, thank you for all your help.

[philipjohn]

If my High school teacher was this good, I would be an Engineer now.

[derekowens]

@Sahand119 At that point in the problem, we are trying to find the maximum height, which occurs at the midpoint of the flight, so we use the time at the midpoint of the flight, which would be half of the total. Hope that helps!

[monkieful]

Good job definitely made it much easier to understand. my teacher is making it so difficult, you've made it simple.

[kozhayachallita]

thank you fr, its all so clear now . great video

[maedotwondesen]

GREAT EXPLANATION!!! THANK YOU VERY MUCH!! KEEP IT UP

[adonisslater]

great help thank you I got it was a big problem I could not get it before, please add videos with fluids problems

[derekowens]

@gareler No! If the angle is measured from the horizontal, then use the sine function to get the vertical component.

If you wanted to use the 20 degree angle, then use the cosine function.

But in general, we use sine for vertical and cosine for horizontal, and always measure the angle relative to the horizontal.

[fayeduddin]

Guys, you can also solve this one step by using max height of a projectile formula: (V^2sin^2theta)/2g

[beta]

gravity is always downwards. Since the motion is upwards (by default, we'll assign it as positive) and gravity is negative cause it's downwards.
It's not necessary that the upward motion is always positive. If the motion was downwards, both woulda been positive.

[monkieful]

keep making videos still taking physics 2 thermodynamics, etc. collisions are confusing to me elastic, inelastic ? and rotational motion your vids are helping a lot

[shinable]

Thanks, I was wondering why you are using v = v0 + at? instead 1/2at^2?

[XxPinoyBroxX]

You made me hella confuse of what to do with that total time (10.16) then I realized it wasn't necessary to put that there because the formula doesn't include the total.. -_-

[loveeyou]

why is it that as you have make the upward is positive... and your acceleration is negative?

[mamumich]

I took the acceleration as positive so my answer is 142.81 will this be considered correct?

[nychimp]

Now I'm confused. Isn't your total time 5.08s because your Vf is also 0!!!!

[nychimp]

@gofish8195 Hey, thanks for responding! Thank G-d, I'm done learning physics :)