Question

A very small 100-g object is attached to one end of a massless 10-cm rod that is pivoted without friction about the opposite end. The rod is held vertical, with the object at the top, and released, allowing the rod to swing. What is the speed of the object at the instant that the rod is horizontal?

Answer 1

Answer:

1.40071 m/s

Explanation:

m = Mass of object = 100 g

v = Velocity of object

h = Height of drop = 10 cm

g = Acceleration due to gravity = 9.81 m/s²

Here, the loss of potential energy is equal to the gain in kinetic energy as energy is conserved

$mgh=\frac{1}{2}mv^2\\\Rightarrow gh=\frac{1}{2}v^2\\\Rightarrow v^2=2gh\\\Rightarrow v=\sqrt{2gh}\\\Rightarrow v=\sqrt{2\times 9.81\times 0.1}\\\Rightarrow v=1.40071\ m/s$

The speed of the object at the instant that the rod is horizontal is 1.40071 m/s