Answer:
D. in a closed system, an object's momentum before a collision will equal its momentum after the collision.
Explanation:
As we know by newton's II law we have

so we will have
F = net force on the system
= change in momentum
so we can say if the momentum is conserved or the initial momentum of the system will be equal to the final momentum of the system
then we will say that

so net force on the system must be ZERO
so in such type of questions the system must be isolated and there is no external force on it
so correct answer will be
D. in a closed system, an object's momentum before a collision will equal its momentum after the collision.
A. F=mg
= 41.63kg x 9.8m/s²
= 407.974
= 408N (3 significant figure)
B. F=mg
632N= y x 9.8m/s²
y= 632 ÷ 9.8
y = 64.48
y= 64.5kg (3 significant figure)
A.gold is the answer. As it's density is 19.32 grams per cubic centimeter which is lot more than the other substances.
A scalar quantity is a measurement of a quantity, like temperature, or mass.
All metals except potassium and sodium, have a property known as malleability. Malleability is the quality of something that can be shaped into something else without breaking. So when aluminium and copper are hammered they will not break. Rather they will change shape and become thin or flat at the area where its hammered.
All Non- metals except diamond are brittle in nature, so when we hammer it , they will break down into pieces. So when ice and glass will be hammered they will shatter into pieces.