Question

Two stones are projected from the top of a tower 100m high, each with a velocity of 20m/s,one is projected vertically upwards and the other vertically downwards. (a) calculate the time to each stone takes to reach the ground (b)

Answer 1

Answer:

stone projected vertically upward

height upto which it goes above(h) can be calculated as

v^2=u^2+2aS

v=0{final speed will be zero at the top}, a= negative{against gravity}

u^2=2aS

20×20= 2×10× h

h=20

total height from which it fall in the end= 100+20

=120

height travelled = ut + 1/2gt^2

120= 0+1/2×10t^2

t^2=24

t=2√6sec

v^2=u^2 +2a(total height)

v^2=0+ 2×10×120

v=20√6

stone projected vertically downward

v^2=u^2+2aH

v^2=20×20+ 2×10×100

=400+2000

=2400

v=20√6

v=u+gt

20√6=20+10t

2√6-2=t

there is your answer i wish i helped you if not sorry