Respuesta :
Here in this case we can use energy conservation law to find out the speed
As per energy conservation we know that
initial kinetic energy + initial potential energy = final kinetic energy + final potential energy
[tex]K_i + P_i = K_f + P_f[/tex]
[tex]0 + 0.5(9.8)(1) = \frac{1}{2}(0.5)v^2 + (0.5)(9.8)(0.8)[/tex]
[tex]0.5(9.8)(1) - 0.5(9.8)(0.8) = \frac{v^2}{4}[/tex]
[tex]0.98 = \frac{v^2}{4}[/tex]
[tex]v = 1.98 m/s[/tex]
so the speed of the pendulum bob is approx 2 m/s when it is 0.8 m above the floor
When the Bob is 0.8 m above the floor,the speed is; 1.98 m/s
We are given;
Mass of pendulum bob; m = 0.5 kg
Initial height; h1 = 1 m
Final height; h2 = 0.8 m
From conservation of energy, we know that;
PE1 + KE1 = PE2 + KE2
Formulas for potential and kinetic energy are;
KE = ½mv²
PE = mgh
- Now, Initial kinetic energy; KE1 = 0 J
Thus;
(0.5 × 9.8 × 1) + 0 = (0.5 × 9.8 × 0.8) + ½ × 0.5 × (v_2)²
Divide through by 0.5 to get;
9.8 = 7.84 + ½(v_2)²
(v_2)² = 2(9.8 - 7.84)
v_2 = 1.98 m/s
Read more about conservation of energy at; https://brainly.com/question/166559
