# Homework Help: Applications of Newton's Law

1. Mar 29, 2016

### alexandria

1. The problem statement, all variables and given/known data

2. Relevant equations
no equations required

3. The attempt at a solution

ok so i collected some information about bob-sledding, but i don't know if i've identified the role that friction plays for the athlete and their shoes in the sport, and i've only come up with one suggestion for improving the footwear, i cant think of anything else that would improve the athlete's footwear??
any help would be appreciated, thanks.

Here is the information i found:
Bob-sledding:

- The athletic shoe must be designed to incorporate spikes in order for the athletes to gain traction between them and the ice.

- The friction between the track and the bobsled is not a high amount because the ice has a smooth surface. The less friction there is, the faster the bobsled tends to go, because there is no opposing force to slow the sled down.

- Since the ground is ice, it is more lubricated and slippery, therefore it has little friction, and so athletes must wear shoes that will provide them with grip.

- When athletes apply force to the ground, they propel themselves forward. In this case, however, there is little friction between the athlete and the ice, so instead of propelling forward, the athlete would slip backwards. These situations can be avoided if athletes use shoes that have small spikes attached to them. The spiked shoes would create traction, so the athlete can propel forward without falling. This is also necessary, so teams can gain traction when pushing their sleds into motion downhill.

- Grip and dynamics are two important factors in this sport

so if i wanted to make two suggestions for improving the footwear:
1) Bob-sledding shoes should be made with small spikes at the bottom, for traction between the athlete and the ice.
2) i cant think of another suggestion??

2. Mar 30, 2016

### Simon Bridge

You have successfully identified that friction is important for the running-pushing part of the event ... you want the shoes to increase friction.
Note: bobsled shoes already include spikes in the soles ... so if you tell the manufacturer "hey, add spikes" they will be like: "we already do...".
So you need to look more closely at the specifics. i.e. would bigger spikes help? Could another type of surface be used to help? Are there cases where bobsledders slip over despite their shoes that you could help fix? Note: you don't have to come up with something practical.
http://www.olympic.org/bobsleigh-equipment-and-history

But - specifically you want to demonstrate your understanding of friction.
There are 4 marks so you probably need to say at least 4 things, two of which should be suggested improvement and the other two probably why each is an improvement (in terms of friction).

3. Mar 30, 2016

### alexandria

two improvements:
1) Canadian researchers have created a new rubbery material made up of 'thermoplastic polyurethane', a type of rubbery plastic, which is embeedded with tens of thousands of microscopic glass fibres. These glass fibres act as tiny spikes that grip to the ice. This new rubber can be incorporated in the bobsled athletic shoe design, as the sole of the shoe. This can provide the athlete with grip and create that traction needed between them and the ice. It will also solve the 'no-friction' issue, as the shoe will support the athletes as they move around on the ice, while at the same time preventing them from slipping or falling.
2) the sole of the athletic shoe should have a rough textured surface, specifically with added treads, inorder to maximize friction with the ice
Ice spikes should be large enough to perforate the ice, so the athlete has a better grip.

4. Mar 31, 2016

### alexandria

ok so here is my final letter to the athletic shoe company's research department, does this sound right?
47.

Dear research department,

A lot of thought and consideration must be done in order to create the ideal athletic shoe that will provide benefit for athletes in their games. Making the perfect athletic shoe for Bob-sledding requires that you take into account the forces acting on the person and the bobsled. One of these forces is friction. As we all know, Bobsledding is a winter sport, meaning it takes place outside on the ice. The friction between the track and the bobsled is not a high amount because the ice has a smooth surface. The less friction there is, the faster the bobsled tends to go, because there is no opposing force to slow the sled down. Not only does friction apply to the bobsleds, but also to the athletic footwear. Since the ground is ice, it is more lubricated and slippery, therefore it has little friction, and so athletes must wear shoes that will provide them with grip. When athletes apply force to the ground, they propel themselves forward. In this case, however, there is little friction between the athlete and the ice, so instead of propelling forward, the athlete would slip backwards. These situations can be avoided if athletes use shoes that maximize friction on the ice. So how can you go about doing this? What can you incorporate in your shoe design to solve the ‘frictionless’ issue? Here are two suggestions for improving your footwear in this sport:
1) Canadian researchers have created a new rubbery material made up of 'thermoplastic polyurethane', a type of rubbery plastic, which is embedded with tens of thousands of microscopic glass fibres. These glass fibres act as tiny spikes that grip to the ice. This new rubber can be incorporated in the bobsled athletic shoe design, as the sole of the shoe. This can provide the athlete with grip and create that traction needed between them and the ice. It will also solve the 'no-friction' issue, as the shoe will support the athletes as they move around on the ice, while at the same time preventing them from slipping or falling.
2) Spiked shoes are also a good option, spikes on the sole of the shoe would create traction. Spikes should be large enough to perforate the ice so the athlete can propel forward without falling. This is also necessary so teams can gain traction when pushing their sleds into motion downhill.
Those are two suggestions for improving the footwear used in bobsledding. It is always important to account for the forces (such as friction and gravity) that play a role for the athletes and their shoes in the game. Only then can you manufacture an athletic shoe that provides benefit for the athlete.

5. Apr 1, 2016

### Simon Bridge

Note: You can slip on ice that does not have a smooth surface, ie chipped or scored ice.
http://dujs.dartmouth.edu/2013/04/what-causes-ice-to-be-slippery/#.Vv8CCo6Ya2c

Look through your letter and single out the parts that reveal your understanding of friction.
You do have two suggestions though ... what will work depends on what the person marking the letter wants to see so you'll have to use your own judgement there.

I'd look for what you understand about friction: what it is and how it works.
So what is it about how friction works that having spikes puncture the ice deals with, for example?