Kinetic Energy in Circular Motion: Is 1/2 m v^2 Still Applicable?

In summary, for circular motion, the kinetic energy can be calculated using the equation 1/2 m v^2. However, for more complex objects, such as a physical pendulum, the moment of inertia and rotational kinetic energy should be taken into account. For a point mass, the direction of motion does not affect the calculation of kinetic energy.
  • #1
JiggaMan
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Homework Statement


in circular motion (e.g. a pendulum) is the kinetic energy still 1/2 m v ^2 or is it a different equation?

Homework Equations


1/2 m v ^2

The Attempt at a Solution

 
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  • #2
It depends on what the object is. For a point mass at the end of a massless string you might use 1/2 m v^2. For a more complicated object that can't be viewed as a point mass you'll want to look at the moment of inertia and rotational kinetic energy. Investigate: "Physical Pendulum".
 
  • #3
Just to add: for a point mass, the kinetic energy depends on the speed (##|\vec{v}|^2##) rather than the (vector) velocity, so the direction of travel (e.g. circular motion) doesn't matter.
 

1. What is the significance of 1/2 m v^2 in a circle?

The term 1/2 m v^2 in a circle represents the kinetic energy of an object moving in a circular path. It is derived from the formula for kinetic energy, where m represents the mass of the object and v represents its velocity.

2. How is 1/2 m v^2 in a circle different from 1/2 m v^2 in a straight line?

In a circle, the velocity of the object is constantly changing as it moves along the curved path. This means that 1/2 m v^2 in a circle is constantly changing, while 1/2 m v^2 in a straight line remains constant as long as the velocity is constant.

3. Can 1/2 m v^2 in a circle ever be negative?

No, 1/2 m v^2 in a circle can never be negative. This is because mass and velocity are always positive values, and squaring them will result in a positive value. Therefore, the kinetic energy of an object moving in a circle will always be a positive value.

4. How is 1/2 m v^2 in a circle related to centripetal force?

The term 1/2 m v^2 in a circle is directly related to centripetal force, as it is a part of the formula for centripetal force (F = m v^2 / r). This shows that the kinetic energy of an object moving in a circle is directly linked to the amount of centripetal force acting on it.

5. Can 1/2 m v^2 in a circle be used to calculate the speed of an object in a circular motion?

No, 1/2 m v^2 in a circle cannot be used on its own to calculate the speed of an object in a circular motion. This term represents the kinetic energy of the object, not its speed. To calculate the speed, we need to use the formula v = √(r * F / m), where r is the radius of the circle, F is the centripetal force, and m is the mass of the object.

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