All that friction

red ford focus vehicle driving on sand under blue daytime sky
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Today, I’m going to admit to being a geek and share some of my enthusiasm for physics. Yes, it does have some relevance for faith so please be patient.

Why don’t things keep on moving?

One of the hardest things for those new to physics to understand is Newton’s first law of motion: I’ll try to put it in plain English.

An object which is not moving will remain still while an object which is moving will continue to move at the same speed and in the same direction UNLESS an unbalanced force acts on it.

Before your eyes glaze over and you click this post shut, I’ll try to unpick this. Newton’s first law is quite extraordinary. What it says is that if something is moving, it should go on moving in the same direction and at the same speed forever UNLESS a force acts on it.

Okay, you don’t need to be an expert in physics to know that nothing goes on moving at the same speed for ever. If you kick a football, it will arc into the air, it’s speed changing, until it falls back to the earth and comes to a halt. If you drag a heavy bag across the floor, it will stop moving as soon as you stop pulling it.

However, if you were living in space, you would be able to see Newton’s first law in action. Once the space shuttle has got into space, it hurtles around the earth at a speed of 17000 miles per hour even though its engines are switched off. If you threw a ball outside your spacecraft, it would keep on moving at the same speed, basically forever, unless it bumped into something which changed its speed or direction.

Friction explained

Why do objects behave so differently in space and on earth? When we walk or drive over ground which isn’t perfectly smooth, there is a force trying to stop us moving. This force is called friction. It means that we have to keep on putting in effort to do things. If we stop tugging the case, it won’t move. If we don’t keep moving our muscles to put one leg in front of the other, we won’t get anywhere. If we stop pushing down the accelerator which keeps the engine going, our car will roll to a halt.

Sometimes it might seem tempting to wish that we lived in a world without friction. It’s easy to imagine a world where we could step on the pavement and glide down the road without any effort, or where our cars rolled along without having to burn expensive fuel.

Fancy a world without friction?

two girls ice skating
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A world without fiction would be nice, wouldn’t it? Maybe not. Think ice.

A smooth expanse of ice is the closest we get on earth to a friction-free situation. If we step on ice wearing ordinary shoes, we will glide along for a few feet but probably end up falling on our behinds. If we manage, somehow, to keep our balance, we won’t get anywhere fast as we’ll just slide around without going in the direction we want to. It’s the same with cars. No-one wants to drive over a patch of black ice as it’s likely that their car will skid out of control.

Friction might seem like an annoying waste of energy, but the truth is that we need something resisting our motion so that we keep on moving forward in the right direction. In situations when there isn’t enough friction, we need to increase it. For instance, in a snowy area, we can fit tyres with a thicker tread in the winter. I once had the opportunity to visit an underground glacier. To walk on its slick surface, I had to strap crampons over my shoes which bit into the ice creating traction.

The friction of daily life

All this got me thinking about the friction of daily life: all these wee household jobs which have to be done every day, your child’s moods, your spouse’s nagging, the elderly neighbour who needs a visit when you have a hundred things to organise.

And then there are the times in life when you face such huge obstacles that you hardly seem to move at all: the illness of a family member, losing a job, having to move out of your home, school or workplace bullying.

Rather than wishing these difficulties and sufferings away so that we can make rapid progress towards what we think is our goal, should we actually be grateful for them? Like real-life friction are all these apparent challenges actually the force which keeps us steady and balanced. Are they what stops us falling over or sliding off in the wrong direction? Without them, would our strength fail and our faith stagnate, just like unused muscles in a frictionless world?

I don’t know, but it’s worth thinking about.

 

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