Answer:
The average force ≅ 519.44 N.
Explanation:
Impulse = change in momentum of a body
i.e Ft = m(v - u)
where F is the force, t is the time, m is the mass of the body, v is the final velocity and u is the initial velocity.
m = 55.0 g (0.055 Kg), t = 0.00360 s, v = 34.0 m/s, since the ball was initially at rest; u = 0 m/s
So that,
F x 0.00360 = 0.055(34 - 0)
F x 0.00360 = 0.055 x 34
= 1.87
F = 
= 519.4444
The average force exerted on the ball by the club is approximately 519.44 N.
Given
The projectile is in air for a time of t=8 sec
To find
The time it takes to reach the highest point
Explanation
A projectile moves up to the highest point and then again moves down following a parabolic path.
So it will reach the highest point at a time half the time it requires to follow teh parabolic path.
The time taken to reach the highest point is 4 sec
Conclusion
The time taken is 4 sec.