Question

which object produces less pressure-needle,wide belts of the school bag,sharp knife,spear

Answer 1

The Wide belt of the school bag produces less pressure than other given options.

All the other 3 options like needle, sharp knife and spear have narrow ends which are supposed to be sharp and hence they put on more pressure when it touches the skin.

However, the wide belt of the school bag has a broader surface area. As per the formula, P = f/a, the pressure is inversely proportional to area. Therefore, the wider the surface area, lesser is the pressure.

So, from the given options, the wide school belt produces less pressure than others.

Answer 2

The correct answer of your question is " wide belts of the school bag"
This is because the pressure actually depends on two things which are force and the area As the formula is Pressure= Force/Area
Which means the area is inversly proportional to the pressure so more the area less will be the pressure and vice versa for the other condition. 
As out of all options here wide belts of the school has the most area so the pressure produced by it will be the minimum or less as compared to other options.