Answer:
The time when the mass will reach its first maximum velocity is 1.8 s.
Step-by-step explanation:
Given;
mass of the pendulum, m = 3 kg
length of the pendulum, l = 0.8 m
height in which the pendulum is raised to, h = 0.2 m
the mass will reach its first maximum velocity when it returns to its initial position, i.e at the middle (x = 0).
the distance between the initial position of the pendulum and the height in which it is raised is the maximum displacement (A).
If we form a right angle triangle with respect to the height in which the pendulum is raised;
the height of the right triangle, H = L - 0.2 = 0.8 - 0.2 = 0.6 m
the hypotenuse side, = L = 0.8 m
the base of the triangle (opposite side) = A
A² = L² - H²
A² = (0.8)² - (0.6)²
A² = 0.28
A = √0.28
A = 0.529 m
The maximum velocity of the pendulum is calculated as;

The period is calculated as;

Therefore, the time when the mass will reach its first maximum velocity is 1.8 s.