Which of these objects would need the largest force to create an
acceleration of 1 m/s2?
a) 4 kg laptop computer
b) 7 kg cat
c) 15 kg child
d) 30 kg sofa

Newton's second law for an object's motion in one spatial dimension:

F = ma

F is the force, m is the mass, and a is the acceleration.

From this equation, we can tell that, compared to a less massive object, a more massive object will need a bigger force to make it accelerate at the same rate. The 30kg sofa has the most mass out of all the above listed objects, therefore it will take the biggest force to accelerate at 1m/s²

Choice D

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.