T is the time for a whole round.
centripetal acceleration = V^2/R,
20 = 40^2 / R, find R = 40^2/20 = 40*40/20 = 80 m, right?
Now, one round is L = 2*pi*R = 2*pi*80 = 160*pi
And T = L/v (distance/speed) = 160*pi/40 = 4*pi seconds, or ~ 12.57 s
Answer:

Explanation:
As we know that ball travels horizontal distance of 24.7 m with uniform speed 49.4 m/s
so we will have



now in the same time ball is turned by angle

now we know that



now the tangential speed of a point at equator is given as



I believe it is -1.11 m/s^2. I will let you know if its correct
Answer:
Option A
Explanation:
This can be explained based on the conservation of energy.
The total mechanical energy of the system remain constant in the absence of any external force. Also, the total mechanical energy of the system is the sum of the potential energy and the kinetic energy associated with the system.
In case of two stones thrown from a cliff one vertically downwards the other vertically upwards, the overall gravitational potential energy remain same for the two stones as the displacement of the stones is same.
Therefore the kinetic energy and hence the speed of the two stones should also be same in order for the mechanical energy to remain conserved.