Answer:
Quick action was in this as a thought of he knew he could die from this
Explanation:
Given that,
Mass of the ball, m = 1.2 kg
Initial speed of the ball, u = 10 m/s
Height of the floor from ground, h = 32 m
(a) Let v is the final speed of the ball. It can be calculated using the conservation of energy as :



v = -25.04 m/s (negative as it rebounds)
The impulse acting on the ball is equal to the change in momentum. It can be calculated as :


J = -42.048 kg-m/s
(b) Time of contact, t = 0.02 s
Let F is the average force on the floor from by the ball. Impulse acting on an object is given by :



F = 0.8409 N
Hence, this is the required solution.
Explanation:
Here,
object distance(u)=20cm
image distance(v)=80cm-20cm=60cm
focal length(f)=?
we know ,
(1/f)=(1/v)+(1/u)
1/f = 1/60 + 1/20
1/f = (1+3)/60
60 =4f
f=15cm