f.2 science- force

weight= mass x gravity
mass=weight/gravity
gravity=weight/mass
對
由於以上三條公式都是按地球的地心吸力而發現的
所以:拉物件的力(F)=物件的重量(m)x物件的加速度(a)

You have to understand what are "weight", "mass" and "gravity" first before knowing their relationship.
"Mass" is a measure of the "quantity of matter" in an object. "Weight" is the result of the pull of gravity on the object. "Weight" is therefore a foce, which depends on the strength of gravity. Hence, the weight of an object is different when under different gravitational attraction, e.g. at the equator and at the pole; or at sea level and at high altitude, or on another planet apart from earth.
"Gravity" is simply the pull of gravitational attraction. It is descibed quantitatively by the physical term "aceleration due to gravity", which measures the strength of gravity.
The equation relating all these quantities are:
weight = mass x acceleration due to gravity
甘如果係甘我係地球拉1舊野既force又係咩
If you try to pull (raise) an object on earth, you have to exert a force at least equals to the weight of the object.
For example, to raise an object of 10 kg needs a force at least equal to its weight, i.e. 10 x 9.81 N = 98.1 N (weight of the object), where 9.81 m/s2 is the average acceleration due to gravity on earth surface.