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# Kinematics and projectile Tweet

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1. Kinematics and projectile
A rescue plane flying horizontally with speed 30ms-1 and altitude 125m above sea wen it drops a warning flare.Neglecting air resistance abd assuming plane doesnt change its course,speed,altitude,how far from the plane is the flare when it hits the water?
For the above qn on distance travelled by warning flare, I KNOW the answer but when i try to use v2=u2 + 2as for vertical motion to try out new method, i realise the u2 is negative!

For picture 2 the qn is: sandbag was released frm hot air balloon 10m from ground,and it is ascending at 4ms-1.qn is :whats the disp time graph.i chose c but its wrong

For 1st picture on brick it says neglecting air resistance..shouldnt it be a straight line down for the height time graph? I.e answer b? Why isnt answer b?
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Last edited by Vadevalor; 13-07-2012 at 15:21.
2. Re: Kinematics and projectile
A rescue plane flying horizontally with speed 30ms-1 and altitude 125m above sea wen it drops a warning flare.Neglecting air resistance abd assuming plane doesnt change its course,speed,altitude,how far from the plane is the flare when it hits the water?
For the above qn on distance travelled by warning flare, I KNOW the answer but when i try to use v2=u2 + 2as for vertical motion to try out new method, i realise the u2 is negative!

For picture 2 the qn is: sandbag was released frm hot air balloon 10m from ground,and it is ascending at 4ms-1.qn is :whats the disp time graph.i chose c but its wrong

For 1st picture on brick it says neglecting air resistance..shouldnt it be a straight line down for the height time graph? I.e answer b? Why isnt answer b?
For your main question just work out the time it takes for the flare to fall to the ground, work out how far the plane travels in that time then use pythagoras to work out the distance.

For pic 2 it's displacement not height. For pic 1 it's height not speed, it's constant acceleration not constant speed.
3. Still dont get how to know graph shape.Theres no nid to calculate the distance for the warning flare but when i tried to use this formula ~~>v2=u2+2as i got u2 to be negative which is weird.Thts what i need to know

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