a parachutist jumps out of an airplane and accelerates with gravity for 6 s. he then pulls the parachute cord and after a 4s deceleration period descends at a rate of 10m/s for 60 sec, reaching the ground. from what height did the parachutist jump. [g=10m/s sqr]
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at the first, u=0m/s, a=g,v1=?
this v1 is the final velocity after 6 s.
x=0.5×10×6×6=180m.
Again, x is the displacement after 6 s.
Then,v1=60m/s.
Also after 4s it has completed y m.
y=60×4+0.5×10×16=320m.
at the final moment,
the acceleration is again for 10m/s² as mentioned in the question.
so v2 is the final velocity after 4s before the final moment.
as v2=2×10×500=100m/s.
Then, final height=100×60+0.5×10×(60)²=9600m.
hence total height=9600+500=10100m.
this v1 is the final velocity after 6 s.
x=0.5×10×6×6=180m.
Again, x is the displacement after 6 s.
Then,v1=60m/s.
Also after 4s it has completed y m.
y=60×4+0.5×10×16=320m.
at the final moment,
the acceleration is again for 10m/s² as mentioned in the question.
so v2 is the final velocity after 4s before the final moment.
as v2=2×10×500=100m/s.
Then, final height=100×60+0.5×10×(60)²=9600m.
hence total height=9600+500=10100m.
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