Consider this question:

A ball thrown directly upwards into the air takes 10 seconds to return to the thrower. Calculate the projection speed and it's return speed.

Now some people consider both the projection speed and the return speed to be the same. But if the words "ball thrown" and "thrower" is replaced with the words "gun shot" and "shooter", it could change everything, right?

So does the upwards force=downwards force?

One criticism often levelled at soccer is that the game can be unexciting as not many goals are scored in most matches. What would be the likelihood of goals if the rules were changed to allow two footballs to be in play at the same time?

Tony Holkham, Petersfield, Hampshire, UK

If you are hit in the face by a cricket ball, would it be more painful at a distance of 50 centimetres from the thrower's hand, or 5 metres? To put it another way, at what point does the ball start decelerating?

Neil Christie, Adstock, Buckinghamshire, UK

I work at Lord's Cricket Ground and a colleague was asked by a child 'Has anyone ever hit a ball so hard its caught fire'. Fantastic question, and although we said no, I thought it might be interesting to find out at what speed would a cricket have to hit to make this happen?

Thank you

I have a question about Geoff Hurst's famous goal in the final of the 1966 World Cup, and it's not whether it crossed the line.

His shot hit the goal's crossbar, deflected downwards, hit the ground and bounced out, away from the goal. I have seen similar shots since.

Why does a ball that hits the underside of the crossbar nearly always bounce away from the goal after it hits the ground? The more powerful the shot, the more likely it is to do this.

Frank Horseman, Scarborough, North Yorkshire, UK

I know that the dimples on golf balls allow them to fly further. But before dimples, protruding nodules were used. What is the difference between the two? Why are dimples better than nodules?

Billy Vine, Cardiff, UK

Alan Glass, London, UK

Last week I played soccer for the first time in years. The goalkeeper kicked the ball high (probably about 20 metres into the air) and a teammate called to me to head it.

I realise I am lacking in skill, but the power of the ball striking my head knocked me off my feet, bruised my forehead and left me with a dreadful headache. Yet professional footballers seem able to head higher and faster-moving balls with no apparent damage or pain.

What velocities and forces are they dealing with, and why did the ball leave me stunned but not a professional player?

Alan Nicholas, Barrow-in-Furness, Cumbria, UK

Description of image: It has a tiny hole in it (almost visible in the pic) and hairline fractures (not visible in pic). Image taken using a USB microscope. Found the object on my shirt cuff. it measures 0.9mm diameter and is spherical.