Question

When a balloon rising vertically upwards at a velocity of 10 m s 1 is at a height of 45 m from the ground, a parachutist bails out from the balloon. After 3 s, he opens the parachute and decelerates at a constant rate of 5 m s 2. (a) what is the height of the parachutist above the ground when he opens the parachute(b) How far is he from the balloon at ts instant(c) With what velocity does he strike the ground(d) What time does he take in striking the ground after s exit from the balloon(g= 10 m/ s2) Ans(a) 30(b 45 m, (c) 10 m s(d) 5 s.GIVE COMPLETE SOLUTION PLEASE

Answer 1

When the parachutists bails out, he has same velocity of the balloon.

u=10m/s in upward direction.
g=-10ms2 in downward direction
t=3sec
so by second equation of motion:
s=ut+1/at²
=10x3+1/2(-10)x 3x3
=30-45s
=-15m
Here negative sign indicates that it is directed downwards.
So height from the ground when he opened parachute is =45-15=30m

b) time=3sec
balloon rises through 30m
Balloon velocity=10m/s
Hence parachute is 30+15=45m away from balloon.

c) The velocity of parahute=?
 time=3sec

V=u+gt
=10-10x3
=-20m/s directed downwards.
at time t=3sec
u=-20m/s
displacemnt s=-30m
a=+5m/s2 upwards
time taken=t=?
s=ut+1/at²
-30=-20t+5/2 t²
t²-8t+12=0
t²-6t-2t+12=0
t(t-6)-2(t-6)=0
t=6 or 2 sec
if t=6 sec then velocity with which he hits the ground will be V=u+at
V=-20+5x6 =10m/s
which is in upward direction not possible.
Hence t=2sec
V=-20+5x2=-10m/sWhich will be in downward direction.

d)  The total time parachutist takes to hit ground=3s+2s=5sec

Answer 2

Answer:

Explanation: Hope it helps