Answer:
Acceleration=velocity/time.
=80/2=40m/s^2.
Just to correct you - the speed of light is 3.0 x 10^5 km/sec and not 105 km/sec as given by you (maybe it was just a typing mistake from your end).
The average distance between earth and moon would be - 384,000 kms.
This is calculated by the formula -> Distance = Speed x Time.
IF the toss was straight upward, then the kinetic energy it got
from the toss is the gravitational potential energy it has at the top,
where it stops rising and starts falling.
Potential energy = (mass) x (gravity) x (height)
= (0.15 kg) x (9.8 m/s²) x (20 m)
= 29.4 kg-m²/s² = 29.4 joules .
A -..................................is the correct option