A hammer and a feather are dropped from the same height by an astronaut on a planet without air. Which value will be different for the two objects? A. The velocity of the objects
B. The time it takes for them to fall
C. The downward pull of gravity
D. The upward push of air resistance

B. The time it takes for them to fall

Explanation: Hammer and feather will go the same speed to earth because gravity pulls everything at the same strength the only difference is air penetration hammer being less wide for it's size and more heavy, ones reach earth atmosphere will start penetrating air quicker which will make it fall faster.

(newtons first law)

conservation of momentum law states :

momentum before collision = momentum after collision

momentum p (kg-m/s)= mass * velocity

say moving car=1 000 kg, velocity = 10 m/s then p = 1 000*10= 10 000 kg-m/s

say still car = 2 000 kg, velocity = 0 m/s then p = 2 000* 0 = 0 kg-m/s

total momentum prior to collision = 10 000 + 0 = 10 000 kg-m/s

momentum after collision = 10 000 kg-m/s

mass now = 1 000 kg+2 000 kg = 3 000 kg

10 000 = 3 000 kg* velocity m/s

10 000/3 000 = velocity

3.33 m/s = velocity after collision

an impulse is a force applied over time , momentum is exclusive of external forces and a perfect collision is implied