Can somebody answer this question for me please? What would be the most effective way for a scientist to get an idea of the actual age of a rock?

Explanation:

Maximum force for forehead = 6 kN

maximum force for cheek bone = 1.3 kN

Part A:

mass of base ball, m = 140 g = 0.14 kg

initial velocity of base ball, u = 30 m/s

final velocity of base ball, v = 0

Time, t = 0.0015 s

Acceleration is defined a the rate of change of velocity.

Use first equation of motion

v = u + at

0 = 30 + a x 0.0015

a = - 20000 m/s²

Part B:

Force = mass x acceleration

F = 0.140 x 20000

F = 2800 N

Part C:

Force applied on your head is 2800 N.

Part D:

As the force is 2800 N that means 2.8 kN which is less than 6 kN so you are safe.