Time=speed/acceleration
Gravitaional Acceleration=9.8 m/s^2
Speed=24.5 m/s
Time=24.5/9.8=2.5 s
Answer:

Explanation:
We must use conservation of linear momentum before and after the collision, 
Before the collision we have:

where these are the masses are initial velocities of both players.
After the collision we have:

since they clong together, acting as one body.
This means we have:

Or:

Which for our values is:

From the formula,
v=2πr/T
V(velocity is inversely related to T),so when v increases then time period will decrease.
Option a is correct.
Answer:
VR=2
Explanation:
driven=60
driving=30
but VR=driven/driving
VR=60/30
VR=2
hence the velocity ratio VR is 2