Answer:
θ  = 12.95º
Explanation:
For this exercise it is best to separate the process into two parts, one where they collide and another where the system moves altar the maximum height
Let's start by finding the speed of the bar plus clay ball system, using amount of momentum
The mass of the bar (M = 0.080 kg) and the mass of the clay ball (m = 0.015 kg) with speed (v₀ = 2.0 m / s)
Initial before the crash
       p₀ = m v₀
Final after the crash before starting the movement
       = (m + M) v
 = (m + M) v
      p₀ = 
      m v₀ = (m + M) v
      v = v₀ m / (m + M)
      v = 2.0 0.015 / (0.015 +0.080)
      v = 0.316 m / s
With this speed the clay plus bar system comes out, let's use the concept of conservation of mechanical energy
Lower
     Em₀ = K = ½ (m + M) v²
Higher
      = U = (m + M) g y
 = U = (m + M) g y
    Em₀ = 
    ½ (m + M) v² = (m + M) g y
    y = ½ v² / g
    y = ½ 0.316² / 9.8
    y = 0.00509 m
Let's look for the angle the height from the pivot point is
     L = 0.40 / 2 = 0.20 cm
The distance that went up is
      y = L - L cos θ
      cos θ  = (L-y) / L
      θ  = cos⁻¹ (L-y) / L
      θ  = cos⁻¹-1 ((0.20 - 0.00509) /0.20)
       θ  = 12.95º
 
        
             
        
        
        
Kinetic energy is formed when the object is in motion.
Potential energy is the energy that is formed relative to others.
One of the example is Corn flour factory.
Corn turned into flour by a windmill that moved by the waterfall. Movement of the mill is relative to the power given by waterfall (potential energy) and the spinning crushes the corn into flour (kinetic energy)