Question

When a pendulum is swinging, the velocity is highest at which point?

Answer 1

Answer:

The velocity is highest at the center, when the bob is hanging straight down

Explanation:

As the pendulum swings to its highest position, its kinetic energy decreases to 0 on both right and left sides. If we tie a string to an object and let it swing back and forth, we will see that object’s velocity is 0 m/s at the highest points on the left and right sides and it is highest at at the center, when the bob is hanging straight down due to gravitational pull and the stored potential energy.

Answer 2

Answer:

The velocity is highest at the lowest point of the trajectory

Explanation:

We can answer the question by applying the law of conservation of energy. In fact, neglecting friction and air resistance, the mechanical energy of the pendulum is constant during the motion:

$E=K+U=const.$

where:

$K=\frac{1}{2}mv^2$ is the kinetic energy, with m being the mass of the pendulum and v the velocity

$U=mgh$ is the potential energy, with g being the acceleration due to gravity and h the heigth of the pendulum with respect to the lowest position

Since E must remain constant, we see that when K is maximum, U is minimum, and viceversa. This also means that when the velocity (v) is maximum, then the height (h) is minimum, so the pendulum must be at its lowest point.