Science of Sport- Curling

Understanding The Science behind Curling 

Curling stones are thick stone disks made of heavy and polished granite along with a handle attached to the top. The maximum mass of a curling stone is 20 kilograms. Why does a curling stone curve (curl) on the ice? Players “sweep” the ice right in front of the stone to decrease the friction of the stone with the ice. This affects the degree of curl of the stone as it slides down the rink, towards the target.

To understand why a curling stone curls we must analyze the physics of curling. The figure below shows a schematic of the curling physics, for a curling stone rotating clockwise. 

Curling_1 Where: G is the acceleration due to gravity. NF is the resultant normal force exerted on the bottom front half of the curling stone, due to contact with the ice .NB is the resultant normal force exerted on the bottom back half of the curling stone, due to contact with the ice. Since the curling stone is in rotational equilibrium in the plane of the page, the sum of the moments about G in this plane must sum to zero. This means that the normal force NR must exert a momentum in the opposite direction to the momentum caused by R. This is only possible if the line of action of NR is to the left of G (on the bottom front half of the curling stone). Consequently, most of the normal force is acting on the bottom front half, and NF > NB.

It is a known fact that contact pressure with ice melts a very thin layer of water on the surface of the ice. This in turn decreases friction. Thus, the friction is inversely proportional to the amount of contact pressure with the ice. So, as a result of NF > NB, the friction force exerted on the (bottom) front half of the curling stone (due to contact with the ice) is less than the friction force exerted on the (bottom) back half of the curling stone (due to contact with the ice).The figure below illustrates this.

Curling_2Where:  FF is the resultant component of friction force exerted on the (bottom) front half of the curling stone, opposing the direction of rotation FB is the resultant component of friction force exerted on the (bottom) back half of the curling stone, opposing the direction of rotation

As stated previously, FF < FB. As a result, the clockwise rotation of the curling stone causes it to move to the right due to the greater friction force FB. If the curling stone is rotated counterclockwise then FF and FB will be pointing in opposite directions and the stone will instead curl to the left. By imparting spin on the curling stone, friction is induced which steers the stone away from its initial straight line trajectory.

The challenge for curlers is to control the level of curl of the stone, in order to get it where they want in the target area. They do this by controlling the level of friction of the stone with the ice.

Image courtesy : wikipedia

150000 wish a few hundred who represent a Billion !

Rio bound Indian Olympic Contingent Receives wishes from 150,000 children

Spirit of Sports Campaign initiated by LeapStart brought together 150,000 children from across the country to convey best wishes to the Indian Olympic and Paralympic Contingent of 2016

 LeapStart, in partnership with Olympic Gold Quest (OGQ), JSW Sports and GoSports Foundation, recently unfolded a nation-wide campaign in 130 schools, covering 45 cities and over 150,000 children to bid farewell and offer encouragement to the Indian athletes who will be leaving for the 2016 Olympic and Paralymic Games in Rio de Janeiro, Brazil.

Johnson Grammar School Habsiguda
Johnson Grammar School Habsiguda

 

The campaign offered school children from across the country an opportunity of a lifetime to send their wishes to the Indian Olympic contingent by writing personalised messages to their favorite athlete on a piece of cloth that was provided to all schools. The campaign reached out to children not only in major metro cities but also in tier 2 and 3 cities like Rohtak, Rajpura, Hosur, Managlore, Erode, Irungattukottai, Rajahmundry and Kurnool.

Together with the partners, LeapStart arranged for interactive sessions between the athletes and the children at their respective training centers where children presented the pieces of cloth with the wishes.

Babita Kumari _Indian Wrestler presented with the wishes
Babita Kumari – Indian Wrestler presented with the wishes

Speaking on behalf of the female wrestling team, Vinesh Phogat said , “ It was a brilliant gesture from everyone at LeapStart to present all these messages of support.
They keep pepping us up. It was wonderful to receive the signed clothes and I think I speak for Sakshi and Babita when I say that it has already become one of our prized possessions”

The campaig
n saw messages presented to ace shooter Heena Sidhu, shuttler Kidambi Srikanth, Para-swimmer Suyash Jadhav,  boxer Vikas Krishnan and the three marathon runners – Nitendra Singh Rawat, T Gopi and Kheta Ram.

Boxer Vikas Krishan said, “Meeting the kids, sharing a few stories and feeling their enthusiasm really gave me a big lift. It was really heartening to see the children being so interested in Olympics. I am sure all the good wishes will help in motivating me to achieve glory for the nation at Rio.”

“All the athletes have worked tirelessly and made huge sacrifices to reach the Olympics and it is important that they know that the country stands with them. It is also important to make children aware of the spirit of the Olympics, what it stands for, and hear stories first hand from the athletes themselves”, said Dhruv Nagarkatti, CEO, LeapStart.

The signed piece of cloth was also presented to the men’s Indian National Hockey Team just before they left for Rio from Bangalore.

Indian Hockey Team with the collated wishes from students across Bangalore
Indian Hockey Team with the collated wishes from students across Bangalore
Suyash Jadhav_Paralympic swimmer with students and Dhruv Nagarkatti, CEO, Leapstart
Suyash Jadhav_Paralympic swimmer with students and Dhruv Nagarkatti, CEO, Leapstart