Why do I get electric shocks from some shopping carts/trolleys and sometimes from my car?

Answer 1

This is because of STATIC CHARGE.
This static charge is generally experienced when the temperature is low. The lower the temperature the more you experience it. So basically you can experience it in winters. And you may experience it in almost anything. You can even experience it in plastic chairs. But mostly you will experience it into metals.
You might be knowing that everything is made of atoms and these atoms contain Proton (+), Neutrons and Electrons (-). Some objects are good conductors of electrons.
The reason for experiencing this Static charge is that when we wear woolen clothes in winter it creates charge in our bodies. Charge can also be created into the places near the electronic things like Server rooms, Computer Rooms etc where there is an abundance of electronic charge.
This charge gets transferred to the objects we touch and then to other people or vice-versa. That cause shock. Sometimes you will even see a spark.
Hope this explanation helps.

Answer 2

In your car: static is built up when you enter/exit and your cloths brush along the seat. When you come close enough to a conductive point, the static discharges.

With shopping carts, it is created between you shoes and the floor (you can do this at home with your sock and the rug - endless hours of fun shocking the family) but the discharge works the same. You can prevent this by simply wearing different shoes, you just haven't noticed all the times you didn't get shocked.

Answer 3

static electricity...