heavier bodies need greater initial effort to put them inmotion. why?

Hi,

Heavier body have grater mass which leads to greater force requirement to put them in motion.

Force is given by

F=ma

Therefore, if m is greater than required force F is greater.

Secondly, the inertia of rest of heavier object is greater than the lighter object hence the greater initial effort is required.

Hope this helps,

Good luck