Question

The image shows Mary happily swinging in the park. There are

three positions shown in the image: A, B, and C. Position B is
located at the very bottom of the swing arc and has the lowest
height.

Choose the correct swing positions to complete the sentence.

Kinetic energy is highest at point [ Choose... ] and Lowest at point [ Choose...]

Choose #1 Options - C, B , A
Choose #2 Options - B, A , C

Answer 1

Kinetic energy is highest at point B and Lowest at point A

Step-by-step explanation:

The kinetic energy is directly proportional to the square of velocity. Therefore, the kinetic energy will be maximum at the point where the velocity is maximum. An it will be lowest at the position where the speed is the lowest. The speed is maximum at point B, because its the mean position. Hence, K.E will be max at B. Also speed is lowest at the highest point so, Kinetic Energy will be lowest at point A.

Another method can be used as follows:

Since, there are two energies present here, namely kinetic energy and potential energy that are interchanging with each other. From law of conservation of energy the sum of kinetic energy and potential energy must be equal at each point. Potential energy is directly proportional to height of object. So, the potential energy will be maximum at point A due to maximum height and consequently Kinetic energy will be minimum at point A. Similarly, the potential energy will be minimum at point B due to minimum height and consequently Kinetic energy will be maximum at point B. Therefore,

Kinetic energy is highest at point B and Lowest at point A