depends on where you live, where you ride, and what the law says about an unicycle. If you're on private property you can ride anything and any way. Where I'm at unis are legally seen as toys, and not as bicycles, which means that bicycle helmet laws don't apply.
It is totally stupid to ride karts anywhere without a helmet, legal or not.
yes
yes
you have to wear a helmet whenever you ride a bike or you will be fined
its legal but u must where a helmet
She was able to ride the unicycle very well.
A neighbour allows his 6 year old son to ride a petrol/diesel driven child size motorcycle on the road on our housing estate, and without a safety helmet. Is this legal here in the UK?
Depends on the state you are riding in. For example, here in indiana its legal to ride without a helmet. But if you are riding and you cross over to Ohio you need to wear a hemet. You will be fined. Furthermore, it is very dangerous, because if you fall off your bike or crash into something it is likely that you hurt your head seriously.
Can - sure. But it will increase the risk of head injuries a little, and in some places wearing a helmet while riding is a legal requirement.
Yes
Of course not
I see no reason why you would not be able too.