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# M1 help (mind blank :() watch

1. A projectile is thrown upwards fom the edge of a cliff. It reaches a maximum height after 5 seconds ignoring air resistance and assuming g is 10's^2

Calculate the maximum height of the projectile.

So i know V=0 A=-10 and t = 5 trying to find X (displacment)

so i use x=VT- 1/2 AT^2

so i get x=-1/2 (-10) -1/2(5)^2 = -7.5 which is obv wrong so is the answer 7.5 and i put a minus in the (-5)?
2. (Original post by hazbaz)
A projectile is thrown upwards fom the edge of a cliff. It reaches a maximum height after 5 seconds ignoring air resistance and assuming g is 10's^2

Calculate the maximum height of the projectile.

So i know V=0 A=-10 and t = 5 trying to find X (displacment)

so i use x=VT- 1/2 AT^2

so i get x=-1/2 (-10) -1/2(5)^2 = -7.5 which is obv wrong so is the answer 7.5 and i put a minus in the (-5)?
The five should be a minus 5, and you said V=0, so it cancells down to
3. When i do this the answer is still -7.5 -1/2(-10) -1/2(-5)^2=-7.5
4. (Original post by hazbaz)
A projectile is thrown upwards fom the edge of a cliff. It reaches a maximum height after 5 seconds ignoring air resistance and assuming g is 10's^2

Calculate the maximum height of the projectile.

So i know V=0 A=-10 and t = 5 trying to find X (displacment)

so i use x=VT- 1/2 AT^2

so i get x=-1/2 (-10) -1/2(5)^2 = -7.5 which is obv wrong so is the answer 7.5 and i put a minus in the (-5)?
Should be a plus instead of minus, no? and why do you have two "1/2" in the final line?

Spoiler:
Show
I get x=125 for my answer

It looks like you haven't used the formula properly
5. Initial velocity = ?
Final velocity = 0

This was your mistake, try it again/

For the equation x=ut+(a2^2)/2 you have taken the final velocity for intial. thats your mistake
6. (Original post by hazbaz)
When i do this the answer is still -7.5 -1/2(-10) -1/2(-5)^2=-7.5

Then you sub in your (correct) values from the first post (A= -10, V=0 t=5)

It shouldn't come out at -7.5 nor 7.5.
7. [QUOTE=n_251]Should be a plus instead of minus, no? and why do you have two "1/2" in the final line?

Spoiler:
Show
I get x=125 for my answer

never mind i got what you mean now IM SUCH A FAIL I DONT DESERVE TO DO MATHS A LEVEL
8. (Original post by hazbaz)
never mind i got what you mean now IM SUCH A FAIL I DONT DESERVE TO DO MATHS A LEVEL
Nah, everyone has off days...

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