For a car of weight 9000 n the recommended tyre pressure is 18 n/cm².find
the area of each tyre in contact with the ground

mathematically,

but weight= Force.

given pressure

18N/cm^2

and Force = 9000N

making area the subject in the relation above.

substitute their values into the equation

when insulating materials rub against each other, they may become electrically charged . electrons , which are negatively charged, may be 'rubbed off' one material and on to the other. the material that gains electrons becomes negatively charged. the material that loses electrons is left with a positive charge.

grav potential energy