czj1997
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(Take g = 10ms^-2 in this question)
A balloon is moving vertically upwards with a steady speed of 3ms^-1. When it reaches a height of 26m above the ground an object is released from the balloon. The balloon then accelerates upwards at a constant rate of 2ms^-2. Find:

i) The greatest height of the object above the ground
ii) the speed of the object as it strikes the ground
iii) the time taken by the object from leaving the balloon to striking the ground
iv) the speed of the balloon as the object strikes the ground


I just don't really understand this question so any help is really appreciated!!! :-)
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Andy98
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(Original post by czj1997)
(Take g = 10ms^-2 in this question)
A balloon is moving vertically upwards with a steady speed of 3ms^-1. When it reaches a height of 26m above the ground an object is released from the balloon. The balloon then accelerates upwards at a constant rate of 2ms^-2. Find:

i) The greatest height of the object above the ground
ii) the speed of the object as it strikes the ground
iii) the time taken by the object from leaving the balloon to striking the ground
iv) the speed of the balloon as the object strikes the ground


I just don't really understand this question so any help is really appreciated!!! :-)
What do you remember of the SUVAT equations?
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czj1997
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(Original post by Andy98)
What do you remember of the SUVAT equations?
basically the 5 equations... was recently introduced to this topic and my teacher rushed it through so I am a bit lost -

thought i could use the v^2 = u^2 +2as equation for the first part, substitute v=0, u=3, a=-10 (???) but I'm not sure where to go from there :ashamed2:
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Andy98
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(Original post by czj1997)
basically the 5 equations... was recently introduced to this topic and my teacher rushed it through so I am a bit lost -

thought i could use the v^2 = u^2 +2as equation for the first part, substitute v=0, u=3, a=-10 (???) but I'm not sure where to go from there :ashamed2:
That looks right to me - just have to rearrange to get s

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Riesel
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Rule number one in mechanics: draw a graph! Even if one is given.

Write down what you know, v for final velocity, u for initial velocity, t for time, a for acceleration and s for displacement.

For SUVAT you'll need 3 known variables and the one you need I usually write it down as (in your case would be) s = ?.

You know a, u, v of the object. Select the equation with the 4.

v= u + at
s = 0.5t(v + u)
v^2 = u^2 + 2as
s = ut + 0.5at^2

iii) is the only one that I can see being a problem to you so here's a hint:u is given, v is taken from ii), a is given, s is given. So you can pick any equation for this, use multiple equations to verify your result.

Think about the direction. If you treat upwards as positive i.e. v = +3m/s then acceleration that's downwards (due to gravity) will obviously be...
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Andy98
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(Original post by Riesel)
Rule number one in mechanics: draw a graph! Even if one is given.

Write down what you know, v for final velocity, u for initial velocity, t for time, a for acceleration and s for displacement.

For SUVAT you'll need 3 known variables and the one you need I usually write it down as (in your case would be) s = ?.

You know a, u, v of the object. Select the equation with the 4.

v= u + at
s = 0.5t(v + u)
v^2 = u^2 + 2as
s = ut + 0.5at^2

iii) is the only one that I can see being a problem to you so here's a hint:u is given, v is taken from ii), a is given, s is given. So you can pick any equation for this, use multiple equations to verify your result.

Think about the direction. If you treat upwards as positive i.e. v = +3m/s then acceleration that's downwards (due to gravity) will obviously be...
Bit in bold ain't true.
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Riesel
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(Original post by Andy98)
Bit in bold ain't true.
Oh yes, sorry. Any equation with t. So not v^2 = u^2 + 2as but you can still plug in your numbers to verify the results.
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Andy98
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(Original post by Riesel)
Oh yes, sorry. Any equation with t. So not v^2 = u^2 + 2as but you can still plug in your numbers to verify the results.
Correct
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