A golf ball has a mass of 0.05 kg. It is initially at rest, but after being struck by a golf club it is given a speed of 30 m/s. The club and the ball are in contact for 2 ms (.002 seconds).

To solve this problem, we will use the principle of conservation of momentum, which states that the total momentum of an isolated system remains constant before and after a collision.

Step 1: Calculate the initial momentum of the golf ball.
The initial momentum (P_initial) of the golf ball can be calculated using the formula:
P_initial = mass × velocity

Given:
Mass of the golf ball (m) = 0.05 kg
Initial velocity (v_initial) = 0 m/s (at rest)

Therefore, the initial momentum (P_initial) is:
P_initial = 0.05 kg × 0 m/s = 0 kg·m/s

Step 2: Calculate the final momentum of the golf ball.
The final momentum (P_final) of the golf ball can be calculated using the same formula as above:
P_final = mass × velocity

Given:
Mass of the golf ball (m) = 0.05 kg
Final velocity (v_final) = 30 m/s

Therefore, the final momentum (P_final) is:
P_final = 0.05 kg × 30 m/s = 1.5 kg·m/s

Step 3: Calculate the change in momentum.
The change in momentum (ΔP) can be calculated by subtracting the initial momentum from the final momentum:
ΔP = P_final - P_initial

Substituting the values:
ΔP = 1.5 kg·m/s - 0 kg·m/s = 1.5 kg·m/s

Step 4: Calculate the average force applied to the golf ball.
The average force (F_avg) exerted on an object can be calculated using the formula:
F_avg = ΔP / Δt

Given:
Time of contact (Δt) = 2 ms = 0.002 seconds

Therefore, the average force (F_avg) is:
F_avg = 1.5 kg·m/s / 0.002 seconds = 750 N

Hence, the average force exerted on the golf ball is 750 Newtons.